The Nursery-Book: A Complete Guide to the Multiplication and Pollination of Plants

THE

NURSERY-BOOK

A COMPLETE GUIDE

TO THE

Multiplication and Pollination of Plants

By L. H. BAILEY

New York:
The Rural Publishing Company
1891

By the Same Author.

Horticulturist’s Rule-Book.

A Compendium of Useful Information for Fruit Growers, Truck Gardeners, Florists and others. New edition, completed to the close of 1890. Pp. 250. Library edition, cloth, $1. Pocket edition, paper, 50 cents.

Annals of Horticulture

FOR THE YEARS 1889 AND 1890.

A Witness of Passing Events, and a Record of Progress. Being records of introductions during the year, of new methods and discoveries in horticulture, of yields and prices, horticultural literature and work of the experiment stations, necrology, etc. Illustrated. 2 vols. Library edition, cloth, $1 per vol. Pocket edition, paper, 50 cents per vol.

[PREFACE.]

This little handbook aims at nothing more than an account of the methods commonly employed in the propagation and crossing of plants, and its province does not extend, therefore, to the discussion of any of the ultimate results or influences of these methods. All such questions as those relating to the formation of buds, the reciprocal influences of cion and stock, comparative advantages of whole and piece roots, and the results of pollination, do not belong here.

In its preparation I have consulted freely all the best literature of the subject, and I have been aided by many persons. The entire volume has been read by skilled propagators, so that even all such directions as are commonly recommended in other countries have also been sanctioned, if admitted, as best for this. In the propagation of trees and shrubs and other hardy ornamentals, I have had the advice of the head propagator of one of the largest nurseries in this country. The whole volume has also passed through the hands of B. M. Watson, Jr., of the Bussey Institution of Harvard University, a teacher of unusual skill and experience in this direction, and who has added greatly to the value of the book. The articles upon orchids and upon most of the different genera of orchids in the Nursery List, have been contributed by W. J. Bean, of the Royal Gardens, Kew, who is well known as an orchid specialist. I have drawn freely upon the files of magazines, both domestic and foreign, and I have made particular use of Nicholson’s Illustrated Dictionary of Gardening, Vilmorin’s Les Fleurs de Pleine Terre, Le Bon Jardinier, and Rümpler’s Illustriertes Gartenbau-Lexikon.

It is believed that the Nursery List contains all the plants which are ordinarily grown by horticulturists in this country either for food or ornament. But in order to give some clew to the propagation of any which are omitted, an ordinal index has been added, by which one can search out plants of a given natural order or family. It cannot be hoped that the book is complete, or that the directions are in every case best for all regions, and any corrections or additions which will be useful in the preparation of a second edition are solicited.

L. H. BAILEY.

Ithaca, N. Y., Jan. 1, 1891.

[CONTENTS.]

NURSERY.—An establishment for the rearing of plants. In America the word is commonly used in connection with the propagation of woody plants only, as fruit-trees and ornamental trees and shrubs. This is erroneous. The word properly includes the propagation of all plants by whatever means, and in this sense it is used in this book.

Tabular Statement of the Ways in which Plants are Propagated.

A. By Seeds.—Seedage.
B. By Buds.		I. On their own roots.		1. By undetached parts.—Layerage.		Root-tips. Runners. Layers proper: Simple. Serpentine. Mound. Pot or Chinese.
				2. By detached parts.		1. By undivided parts.—Separation (Bulbs, corms, bulbels, bulblets, bulb-scales, tubers, etc).
						2. By divided parts.—Cuttage.		Division. Cuttings proper: Of tubers. Of roots. Of stems. Of leaves.
		II. On roots of other plants.—Graftage.		1. By detached scions.		I. Budding: Shield, flute, veneer, ring, annular, whistle or tubular.
						II. Grafting: Whip. Saddle. Splice. Veneer. Cleft. Bark. Herbaceous. Seed. Double. Cutting.
				2. By undetached scions.—Inarching.

[CHAPTER I.]

SEEDAGE.

Seedage.—The process or operation of propagating by seeds or spores, or the state or condition of being propagated by seeds or spores.

There are three external requisites to the germination of seeds—moisture, free oxygen, and a definite temperature. These requisites are demanded in different degrees and proportions by seeds of different species, or even by seeds of the same species when differing widely in age or degree of maturity. The supply of oxygen usually regulates itself. It is only necessary that the seeds shall not be planted too deep, that the soil is porous and not overloaded with water. Moisture and temperature, however, must be carefully regulated.

Fig. 1. Double Seed-Pot.

Regulation of Moisture.—Moisture is the most important factor in seedage. It is usually applied to the seeds by means of soil or some similar medium, as moss or cocoanut fiber. Fresh and vigorous seeds endure heavy waterings, but old and poor seeds must be treated sparingly. If there is reason to suspect that the seeds are weak, water should not be applied to them directly. A favorite method of handling them is to sow them in a pot of loose and sandy loam which is set inside a larger pot, the intermediate space being filled with moss, to which, alone, the water is applied. This device is illustrated in [Fig. 1]. The water soaks through the walls of the inner pot and is supplied gradually and constantly to the soil. Even in this case it is necessary to prevent soaking the moss too thoroughly, especially with very weak seeds. When many pots are required, they may be simply plunged in moss with the same effect. The soil should be simply very slightly moist, never wet. Moisture is sometimes supplied by setting the seed-pot in a shallow saucer of water, or it may be sufficient to simply place it in the humid atmosphere of a propagating-box. Large seeds may be laid upon the surface of the soil in a half-filled pot, covered with thin muslin, and then covered with loose and damp loam. Every day the pot is inverted, the covering taken off and fresh soil is added. A modification of this plan for small seeds can be made by placing the seeds between two layers of thin muslin and inserting them in damp loam, which is frequently renewed to avoid the extremes which would result from watering or from allowing the soil to become dry. In these last operations, no water is applied to the seeds and they constitute one of the most satisfactory methods of dealing with seeds of low vitality. They are essentially the methods long ago used by Knight, who laid such seeds between two sods cut from an old and dry pasture.

Even sound and strong seeds should be watered with care. Drenchings usually weaken or destroy them. The earth should be kept simply damp. To insure comparative dryness in in-door culture, some loose material, as pieces of broken pots or clinkers, should be placed in the bottom of the pot or box to afford drainage. It should be borne in mind, however, that the seed bed should be approximately equally moist throughout its depth. The waterings should therefore be copious enough to moisten the soil throughout. A wet or moist surface over a dry substratum should always be avoided. Error is common here. It is usually best to apply water with a watering-pot, as watering with a hose is apt to wash out the seeds and to pack the soil, and the quantity of water is not so easily regulated.

At first thought, it would appear that the apparently good results following soaking of seeds in many cases, are a contradiction of these statements that seeds may be over-watered. But soaking is usually beneficial only when practiced for a comparatively short time. It is not good practice to soak delicate seeds before sowing, and it is of doubtful utility in most other cases, unless it is necessary to soften the integuments of hard-shelled species, as discussed on [page 17]. The gain in rapidity of germination following soaked, as compared with dry seeds, is really fictitious, inasmuch as germination actually begins in the soaked seeds before the dry samples are sown. The soaked seeds are sown in water rather than in soil, and as conditions are more uniform there, a gain apparently due to soaking may result. In the case of strong seeds which must be planted out-doors in cold or uncongenial soil, a preliminary soaking of from 12 to 24 hours may be beneficial, as it lessens the period which the seeds would otherwise pass in untoward conditions. But soaked seeds, unless of very hardy species, should never be sown out-doors until the soil has become rather dry and warm.

To prevent too rapid drying out, the soil should be firmly pressed about the seeds. The pot or box should be given a shady place, or some covering may be applied to check evaporation. A pane of glass is often placed over the box, being tilted a little at intervals to allow of ventilation and to prevent the soil from becoming soggy or “sour.” A seed-case, with a glass cover, as shown in [Fig. 2], is neat and handy in the treatment of small seeds. A thin covering of fine moss is sometimes given, or a newspaper may be thrown over the soil.

Fig. 2. Seed-Case.

In out-door culture, only a naturally dry and well-drained soil should be chosen for all ordinary seeds, especially for such as are sown in the fall or remain in the ground a long time before germinating. Soils which contain a liberal amount of sand or gravel are especially valuable for this purpose.

To prevent drying in out-door culture, it is important that the earth be well firmed over the seeds. Walking on the row, placing one foot directly ahead of the other, is usually the most expeditious and satisfactory operation, at least with large seeds. Or the earth may be firmed with a hoe or the back of a spade, or a board may be placed upon the row and then be thoroughly settled by walking over it. In the sowing of celery and other small and slow seeds, it is a frequent practice to leave the board on the row until the seeds appear in order to hold the moisture. This is a doubtful expedient, however, for the young plants are apt to be quickly dispatched by the sun when the board is removed. If the board is employed, it should be raised an inch or two from the ground as soon as the plants begin to appear. But the shade of the board is too dense and plants do not grow stocky under it. It is better to use brush or lath screens if protection is desired; or fine litter, if free from weed seeds, may be used. In most cases, however, screens will not be needed by celery and similar seeds if the ground is in the proper condition and is well firmed at planting time. It is always advisable, nevertheless, to place the beds for slow and small seeds where they can be watered occasionally.

Fig. 3. Lath Screen.

There are many kinds of screens in use to prevent the drying out of small seeds in out-door seedage and to protect the young seedlings. These are used also in the shading of cuttings. The common lath screen ([Fig. 3]) is the most useful for general purposes. It is simply a square frame made from common laths laid at right angles in a double series. The interstices between the laths are equal in width to the laths themselves. These screens are laid horizontally upon a light frame-work a few inches above the seeds. The passage of the sun constantly moves the shadows over the bed, and sufficient shade is afforded while thorough ventilation is allowed. This and all other elevated screens are useful in shading and protecting the young plants as well, but when used for this purpose they are usually raised a greater distance above the beds. A brush screen consisting of a low frame covered with boughs, is often used, as shown in [Fig. 4]. This is cheaper than the lath screens, and is equally as good for most purposes. The brush is often laid directly upon the ground, especially in large beds. This answers the purpose of shading, but it does not allow of weeding and it must be taken off soon after the seeds germinate, or slender plants will be injured in its removal. Brush screens are sometimes raised three or four feet to allow of weeding. A screen for frames is shown in [Fig. 5]. It is a simple covering of muslin stretched over the top and sides of a rough frame-work. The cloth is usually omitted from the front side. This style of screens is much used by nurserymen, especially for cutting beds. Whitewashing the sashes also affords good shading. A more elaborate and permanent screen is shown in [Fig. 6]. It is built of slats, usually 3-inch stuff. This shed screen is oftenest used for the protection of tender plants, but it affords an exceedingly useful and convenient place for the storage of pots and boxes of slow-germinating seeds.

Fig. 4. Brush Screen.

Fig. 5. Screen for Frames.

Fig. 6. Shed Screen.

Various frames and covers are employed for in-door seedage, but they are designed to regulate atmospheric moisture and to control temperature. They are more commonly employed in the growing of cuttings, and are therefore described in Chapter IV.

Requirements of Temperature.—Variations in temperature exercise less influence upon seeds than variations in moisture. Yet it is important that the extremes of temperature should not be great, especially in small, delicate or weak seeds. Seeds will endure greater extremes of temperature when dry than when moist. This indicates that germinating seeds must be kept in a comparatively uniform temperature. For this reason it is poor practice to place seed-boxes in a window in full sunlight. Partial or complete shade serves the double purpose of preventing too great heat and too rapid evaporation. Various covered seed-boxes are used for the purpose of maintaining approximately the required temperature, but as they are oftener used in bud-propagation, they are discussed in that connection.

Bottom heat is helpful to germination in most seeds, but, except in the case of certain tropical species, it should not be strong. It is a common practice to place the seed-boxes on moderately cool pipes under benches in a greenhouse. Seeds of hardy annuals and perennials do not require bottom heat, although they may be benefitted by it. If the soil in seed beds should become too cool, watering with warm or tepid water will be found helpful.

It is impossible to give rules for the determination of the proper temperature for different kinds of seeds. In general, it may be said that seeds germinate most rapidly at a temperature a few degrees above that required for the best development of the plant itself. Hardy plants require a temperature of from 50° to 70°, conservatory plants from 60° to 75° or 80°, and tropical or stove plants from 75° to 95°. The plantlets should be removed from these highest temperatures, as a rule, as soon as germination is completed.

In out-door culture, depth of planting has a direct relation to temperature. Seeds may be planted deeper late in the season than early, when the soil is cold and damp. Deep planting probably as often kills seeds because of the absence of sufficient heat as from the lack of oxygen or the great depth of earth through which the plantlet is unable to push.

Preparatory Treatment of Seeds.—Many seeds demand some treatment preparatory to sowing. Nearly all hard and bony seeds fail to germinate, or at least germinate very irregularly, if their contents are allowed to become thoroughly dry and hard. The shells must also be softened or broken in many cases before the embryo can grow. Nature treats such seeds by keeping them constantly moist under leaves or mold, and by cracking them with frost. This suggests the practice known to gardeners as stratification, an operation which consists in mixing seeds with earth and exposing them to frost or to moisture for a considerable time.

Stratification is practiced, as a rule, with all nuts, the seeds of forest trees, shrubs, the pips of haws and often of roses, and in many cases with the seeds of common fruits. It should be performed as soon as possible after the seeds are mature. Small seeds are usually placed in thin layers in a box alternating with an inch or two of sand. Sometimes the seeds are mixed indiscriminately in the sand, but unless they are large it is difficult to separate them out at sowing time. The sand is often sown with the seeds, however, but it is difficult in such cases to distribute the seeds evenly, and in sowing large quantities the handling of the sand entails a considerable burden and becomes an item of expense. It is advisable to pass the sand through a sieve of finer mesh than the seeds, and the seeds can then be sifted out at sowing time. If the seeds are very small or very few in number they may be placed between folds of thin muslin, which is then laid in the sand. Any shallow box, like a gardener’s “flat,” is useful in making stratifications, or with small lots of seeds pots may be used. A flat four inches deep might contain two or three layers or strata of seeds the size of peas.

The disposition of the boxes when filled varies with different operators. Some prefer to bury them. In this case a well-drained sandy slope is chosen. The flats are placed in a trench from one to two feet deep, covered with a single thickness of boards, and the trench is then filled with earth. The seeds usually freeze somewhat, although freezing is not considered necessary unless in the case of nut-like seeds. The object attained in burying is to keep the seeds moist and fresh, inducing the rotting or softening of the coverings, while they are buried so deep that they will not sprout. Seeds of most forest trees should be treated in this manner. They are commonly left in the ground until the second spring, when they are taken up and sown in drills in mellow ground. If good loam to which has been added a little well-rotted manure is used, the seeds or nuts of hardy trees and shrubs may be allowed to germinate and grow for one season in the flats. At the end of the season or the next spring the plants can be transplanted without losing one. This is, perhaps, the best way to handle rare and difficult subjects.

Many growers place the boxes on the surface in some protected place, as under trees or in a shed, and cover them a foot deep with clean straw or leaves. This is a good method for all seeds which are to be sown the following spring, as those of many fruits. If boxes are piled on top each other they should be mulched with moss, else the under ones may become too dry. Or the boxes may be placed without covering in a shed, but they must be examined occasionally to see that they do not become too dry. Precaution must also be taken to keep away mice, squirrels, blue-jays and other intruders.

Large nut-like seeds or fruits, like peach-pits, walnuts and hickory-nuts, are usually buried in sand or light loam where they will freeze. Or sometimes the large nuts are thrown into a pile with earth and allowed to remain on the surface. Freezing serves a useful purpose in aiding to crack the shells, but it is not essential to subsequent germination, as is commonly supposed. All seeds, so far as known, can be grown without the agency of frost if properly handled.

Fall sowing amounts to stratification, but unless the soil is mellow and very thoroughly drained the practice is not advisable. The seeds are liable to be heaved or washed out, eaten by vermin, and the soil is apt to bake over them. Under proper conditions, however, the seeds of fruits and many forest trees thrive well under fall sowing. The seeds should be sown as soon as they are ripe, even if in mid-summer; or if the ground is not ready for them at that time, they may be temporarily stratified to prevent too great hardening of the parts. It is best, however, to allow all green or moist seeds to dry off a few days before they are stratified. Fall sown seeds should always be mulched.

Some seeds rarely germinate until the second year after maturity, even with the best of treatment. The thorns, mountain ash, hollies, viburnums, some roses, and many others belong to this category. Some growers sow them regularly as soon as they are ripe and allow the beds to remain until the seeds appear. This is a waste of land and of labor in weeding, and the best way is to stratify them and allow them to remain until the second spring before sowing.

Partial substitutes for stratification are soaking and scalding the seeds. Soaking may be advantageously practiced in the case of slow and hard seeds, which are not enclosed in bony shells, and which have been allowed to become dry. Seeds of apple, locust and others of similar character, are sometimes treated in this manner. They are soaked for 24 or 36 hours, and it is commonly supposed that if they are exposed to a sharp frost in the meantime, better results will follow. While still wet the seeds are sown. Scalding water may be poured over locust and other seeds to soften their covering. But seeds should not be boiled, as sometimes recommended.

Fig. 7. Bored Seed.

The germination of bony seeds is often facilitated by filing or cutting away the shell very carefully near the germ, or by boring them. A bored nelumbium seed is shown in [Fig. 7].

Treatment with various chemicals has been recommended for the purpose of softening integuments, and also for some power which strong oxidizing agents are supposed to exert in hastening germination itself, but the advantages are mostly imaginary. Secret and patented “germinator” compounds had better be avoided.

Pulpy and fleshy coverings should be removed from seeds before sowing. Soft fruits, like berries, are broken up or ground into a pulp and the seeds are then washed out. This separation may be performed immediately in some cases, but when the pulp adheres to the seed, the whole mass is usually allowed to stand until fermentation and partial decay has liberated the seeds. The pulp will then rise, in most instances, leaving the seeds at the bottom of the vessel. Seeds can be liberated quickly by adding a stick of caustic potash to each pail of water. After the mass has stood an hour or so, the seeds can be rubbed out easily. Even tomato seeds can be cleaned with safety in this manner. Seeds which have thin coverings, as the viburnums and many haws, can be prepared by rubbing them through the hands with sharp sand. Or the scant pulp of such seeds may be allowed to rot off in the stratification box. Fleshy coverings of hard and bony seeds may be removed by maceration. Allow them to stand in water at a temperature of about 75° for one to three weeks, and then wash them out. Resinous coverings are sometimes removed by mixing the seeds with fresh ashes or lime, or by treating them with lye. Hard, thick-walled seeds are rarely injured by the decay of the pulpy covering, but thin-walled seeds should be cleaned, to avoid the possibility of damaging them.[A]

[A] An admirable paper upon the propagation of hardy trees and shrubs from seeds and the treatment of the young seedlings, by Jackson Dawson, may be found in Trans. Mass. Hort. Soc. 1885, part 1, 145, and also in Rep. Sec. Mass. Bd. Agr. 1885, 468.

Sowing.—The soil in which seeds are sown, especially in in-door culture, should be such as to allow of perfect drainage and at the same time to hold moisture. Good potting soil, with a liberal allowance of sharp sand, is the best for general purposes. Pure sand becomes too dense, and leaf mold alone is usually too loose and open. A proper combination of the two corrects both faults. It is impossible to describe a good potting or seed-bed soil. Some experience is essential to the best results in preparing it. It should be of such character that when a damp portion is firmly compressed in the hand it will fall apart when released. It should never bake. Good old garden loam, to which an equal quantity of sand has been added, is usually a good soil for common in-door seedage. There should be no manure in soil used for seeds which produce a delicate growth, as rhododendrons and kalmias. In all such cases, rotted sod or leafy peat forms the best basis. The soil should be sifted and thoroughly fined before seeds are put into it. Seeds usually require lighter soil than that in which the growing plant will flourish. Cocoanut fiber is sometimes used in place of the soil, as it holds moisture, allows of almost perfect drainage, and does not become “sour.” Fine dead sphagnum moss may also be used. Orchid seeds are usually sown on the live moss in which the parent plant is growing; or they may be sown on damp wood or cork. (See under [Orchids], [Chap. VI].) Small seeds, like those of cineraria and calceolaria, germinate well in very old cow-dung obtained from a pasture; the unctuous matters have disappeared, leaving a fibrous remainder. But all things considered, well-prepared soil is the most satisfactory medium which can be used. Seeds of aquatic plants which are to be sown in a pond may be placed in a ball of clay and dropped into the water.

Shallow boxes or “flats” and earthen seed-pans and lily-pans are usually preferable to pots in which to grow seeds. They give more surface in proportion to their contents and require less attention in drainage. If pots are used, the four to six inch sizes are best.

If delicate seeds are sown out-doors, they should be given some protection, if possible. An ordinary hot-bed frame gives the best results. In warm weather or a sunny exposure it will be found desirable to substitute a cloth screen for the sash. A thin or medium water-proof plant cloth, either commercial or home-made, is excellent for this purpose. It may be tacked upon a simple and light rectangular frame which is strengthened at the corners by iron “carriage-corners.” These cloth-covered frames are handy for many purposes, particularly for protecting and supplying some warmth to seed-pans and young seedlings.

It is essential that good drainage be given all in-door seed-pots or seed-beds. A layer of broken pots or other coarse material is placed on the bottom. Many growers place a thin layer of fine dead sphagnum moss or of peat over this drainage material, and it certainly makes a useful addition. It is particularly useful in isolated pots or small boxes, as it holds enough moisture to prevent too rapid drying out, while all surplus water is quickly taken off by the coarse material beneath. Over the moss coarse siftings from the soil may be placed, while on top only the finest and best soil should be used. The smaller the seeds, the more care must be exercised in the sowing.

The proper depth for sowing varies directly with the size of the seed. The chief advantage of very fine soil for small seeds is the greater exactness of depth of covering which it allows. Very small seeds should be sown upon the surface, which has previously been well firmed and levelled, and then covered with a very thin layer of finely sifted soil or a little old and dead moss rubbed through a sieve. This covering should be scarcely deeper than the thickness of the seeds; that is, the seeds should be barely covered. Many prefer pressing the seeds into the soil with a block. Or if one has a close propagating-box, the seeds may remain upon the surface and sufficient moisture will be supplied from the atmosphere. Such fine seeds are rarely watered directly, as even the most careful treatment would be likely to dislodge them. The soil is usually well watered before the seeds are sown, or moisture may be supplied by inserting the pot in water nearly to its rim for a few moments. If water is applied from a hose, a thin cloth should first be spread on the soil to hold it. Celery seeds, in out-door beds, are often sown upon a nicely prepared surface and are then pressed in by means of the feet or a board. Some cover to prevent evaporation should be given all small seeds. This may be a board or a slate slab at first, but as soon as the plants appear glass should be substituted to admit light. (See pp. [11] to [14].)

Large seeds demand much less care as to depth of covering, as a rule. One-fourth or one-half inch is a good depth for most coarse seeds in-doors. If one wishes to gauge the depth accurately, the drills may be made by a planting stick, like that shown in [Fig. 8]. Its flange is made of the required thickness, and it is pressed into the soil until the cap strikes the surface. This is a useful implement in seed testing. Another device for regulating the depth of sowing, particularly in seed testing, is the Tracy planter, shown in [Fig. 9]. It consists of two strips of heavy tin plate about three inches wide, hung upon two wire pivots or hinges some two inches long. At their upper edges and equidistant from either end, the plates are joined by a firm spiral spring, which serves to throw the upper edges apart, and to cause the lower edges to join. This trough is now filled with the required number of seeds, and is then inserted into the earth to a given depth, when the fingers push inward on the spring and the trough opens and delivers the seeds.

Fig. 8. Planting Stick.

Miscellaneous Matters.—The influence which light exerts upon germination is not definitely understood. It is known, however, that seeds will often germinate in full sunlight, if the proper conditions of moisture and temperature can be maintained. Seeds sown upon a moist surface and covered with a glass present an interesting study. But it is well known, on the other hand, that some seeds will not germinate, or will at least appear unevenly, if subjected to sunlight. At least some of the delphiniums, papavers and adonises germinate very imperfectly, if at all, in direct light. It is always advisable to keep germinating seeds in shade or partial darkness, especially as there is nothing to be gained by exposing them. Of course the soil itself is sufficient protection if the seeds are covered.

Fig. 9. Tracy Planter.

It is a common statement that seeds can never revive if allowed to become thoroughly dry after they have begun to sprout. This is an error. Wheat, oats, buckwheat, maize, pea, onion, radish and other seeds have been experimented upon in this direction, and they are found to re-germinate readily, even if allowed to become thoroughly dry and brittle after sprouting is well progressed. They will even re-germinate several times. Wheat, peas and other seeds have been carried through so many as seven germinations after the radicle had grown a half inch or more and the seeds had been sufficiently dried in each trial to render them fit for grinding.

Damping-off is a common ailment of young seedlings and cuttings. The stem becomes brown and constricted at or near the surface of the soil, and it soon rots and falls over. The top of the plant often remains alive and fresh for several days after it has fallen. A fungus is supposed to cause damping-off. The conditions which seem to particularly favor the development of this fungus are a moist and close atmosphere, crowding and careless watering. Plants are particularly liable to damp-off if only sufficient water is applied to keep the surface moist while the under soil remains dry. Hot sand, sifted over the plants, will check it, but there is no complete remedy. Attention to the above suggestions will serve as a preventive.

The transportation of certain kinds of seeds over long distances, especially on sea voyages, is often beset with difficulties. Thick-meated or soft seeds may become too dry if stored in a warm place or too moist if stored in a cool one. The humid atmosphere of the ocean is fatal to some seeds unless they are well protected, and the moist and hot climates of some tropical countries destroy many seeds of cooler regions before they can be planted. Thin-coated seeds demand dryness and air, and bony seeds usually need moisture and a more confined atmosphere. Most seeds may be sent dry and loose in coarse paper packages under all ordinary circumstances; but if they are to traverse very hot and moist climates, they should be sealed in tin cases or very securely wrapped in oiled paper, in which case the seeds should be thoroughly dried before being packed. Small seeds which are liable to become moldy may be packed in finely powdered charcoal. Apple and pear seeds are often imported in this manner. The seeds or fruits of woody plants require more careful management. They should generally be transported in some sort of stratification. A favorite method is to place them in boxes or jars, mixed with naturally moist sand or sawdust, or slightly moist dead sphagnum moss. Some prefer to seal the packages hermetically, but under ordinary conditions this is unnecessary. In transit, the packages should be stored in a medium and uniform temperature. Even acorns, which are often difficult to transport over long voyages, may be carried in this manner with safety. It is important that the soil should not be wet. Natural soil from a dryish and loamy pasture is excellent. In some cases it is better to sprout the seeds in the native country and ship the seedlings in a closed or Wardian case.

It should be borne in mind that actual plantings rarely give so good results as seed tests, from the fact that conditions are more variable. There is often a variation of over fifty per cent. even when the planting has been carefully done. This is proof that liberal seeding should always be practiced.

Spores.—Ferns, lycopodiums and selaginellas are often grown from spores. The general conditions adapted to the germination of seeds are also suitable for the germination of spores, but extra care must be taken with the drainage. If a pot is used, it should be half or more filled with drainage material, and the soil should be rendered loose by the addition of bits of brick, charcoal, cinders or other porous materials. The surface soil should be fine and uniform. Some place a thin layer of brick dust upon the surface, in which the spores are sown. It is a frequent practice to bake the soil to destroy other spores which might cause troublesome growths. The spores should be sprinkled upon the surface and should not be covered. The pot should be set in a saucer of water and it should be covered by paper or a pane of glass if the sun strikes it. Better results are obtained if the pot or pan is placed inside a propagating-frame or under a bell-glass. In place of earth, a block or small cubes of firm peat or sandstone may be employed. The block is placed in a saucer of water and the spores are sown upon its surface. Water should not be applied directly to the spores, as it is apt to dislodge them.

The period of germination varies in different species, but three to six weeks may be considered the ordinary limits. While still very small, the plantlets should be pricked out, and for some time thereafter they should be subjected to the same conditions as before. Spores are so exceedingly small and light that the greatest care must be exercised in growing them. In order to gather them, the fronds may be cut as soon as the sori or fruit-dots turn brown, and stored in close boxes or paper bags.

Note.—For tables of weights and longevities of seeds and quantities required for given areas, consult Horticulturist’s Rule-Book.

[CHAPTER II.]

SEPARATION.

Separation.—The act or process of multiplying plants by means of naturally detached asexual organs, or the state or condition of being so multiplied.

Separation is effected by means of bulbs, bulbels, bulb-scales, bulblets, corms, tubers, offsets, crowns and sometimes by buds.

Bulbs of all kinds are specialized buds. They are made up of a short and rudimentary axis closely encased in transformed and thickened leaves or bulb-scales. These thickened parts are stored with nutriment which is used during subsequent growth. Bulbs occur only in plants which are accustomed to a long period of inactivity. Many bulbous plants are peculiar to dry and arid regions, where growth is impossible during long periods. A bulb is, therefore, a more or less permanent and compact leaf-bud, usually occupying the base of the stem underground and emitting roots from its lower portion. Bulbs are conveniently divided into two great classes—the scaly, or those composed of narrow and mostly loose scales, as in the lily, and laminate or tunicate, or those composed of more or less continuous and close-fitting layers or plates, as in the onion.

Fig. 10. Bulb of Lilium candidum.

Bulbs often break up or divide themselves into two or more nearly equal portions, as in Lilium candidum, shown one-third natural size in [Fig. 10]. The parts may be separated and treated as complete bulbs for purposes of propagation. This division or separation of bulbs proceeds in a different manner in nearly every species, yet it is so obvious that the novice need not be perplexed by it. Almost any breaking apart of these loose bulbs, if only a “heart” or central axis remains in each portion, is successful for purposes of slow multiplication; but when flowers are desired it is usually inadvisable.

Bulbous plants multiply most easily by means of bulbels—often also called bulbules and offsets—or small bulbs which are borne about a large or mother bulb. In some lilies, as Lilium candidum, the bulbels form at the top or crown of the mother bulb, and a circle of roots will be found between them and the bulb; in others, as L. speciosum and L. auratum, they form on the lower part of the flower stalk. In some species the bulbels are few and very large, or even single, and they bloom the following year. In such cases the bulb undergoes a progressive movement from year to year after the manner of root-stocks, the bulb of one year forming a more or less distinct one above and beyond it which continues the species, while the old one becomes weak or dies. This method of bulb formation is seen in the cut of Lilium pardalinum, [Fig. 11]. In the hyacinth the bulbels form at the base of the bulb.

Fig. 11. Bulb of Lilium pardalinum.

Bulbels vary greatly in size and frequency in different species. Sometimes they are no larger than a grain of wheat, and in other plants they are as large as hickory-nuts. In some species they are borne habitually underneath the scales of the mother bulb. These bulbels are often removed when the mother bulbs are taken up, and they are usually planted in essentially the same manner as the bulbs themselves, although it is desirable to place them, at least for the first year, in a bed or border by themselves. Or if they are especially small and delicate they may be planted in pots or flats and be treated about the same as single eye cuttings. In some lilies the bulbels are allowed to remain attached and the whole mass is planted in the fall in close drills. Sometimes the larger lily bulbels will produce flowers the following season, but they usually require the whole of the season in which to complete their growth. The second fall they are ready to be permanently planted. Bulbels of some plants require a longer time in which to mature into bulbs.

Fig. 12. Cut Hyacinth Bulb.

Fig. 13. Hollowed Hyacinth Bulb.

Bulbels are often produced by an injury to the bulb. Growth of stem and leaves is prevented or checked and the energy is directed to the formation of minute buds, or bulbs, in the same manner as adventitious buds form upon a wounded stem. Advantage is taken of this fact to multiply some bulbous plants, and in the case of the hyacinths, at least, the mutilation of bulbs for this purpose is practiced to a commercial extent. Hyacinth bulbs are cut in two, or are slashed in various ways. The favorite method is to make two or three deep transverse cuts into the base of the bulb. The strongest bulbs should be chosen and the operation is performed in spring or early summer when the bulb is taken up. The bulbs are sometimes hollowed out from the under side for half or more of their length. This operation is sometimes performed later in the season than the other, and precaution should be exercised that the bulbs do not become too moist, else they will rot. Hollowed bulbs should be well dried before being planted. Both methods of preparing hyacinth bulbs are shown in Figs. [12] and [13] which are adapted from Gardeners' Chronicle. [Fig. 14] shows a portion of the base of a cross-cut bulb, with the adventitious bulbels. The mutilated bulbs are stored during summer, and are planted in fall or spring. The wounded bulbs produce very little foliage, but at the end of the first season the bulbels will have formed. The bulbels are then separated and planted by themselves in prepared beds. Several years are required for the bulbels to mature into flowering bulbs. Some of the strongest ones may produce flowering bulbs in three years, but some of them, especially those obtained from the hollowed bulbs, will not mature short of six years. This method of propagating hyacinths is confined almost entirely to Holland.

Fig. 14. Cross-Cut Bulb.

The scales of bulbs are often employed to multiply scarce varieties. From ten to thirty of the thicker scales may be removed from the outside of the bulb without serious injury to it. These are treated in the same manner as single eye cuttings. They are usually handled in flats or propagating-frames, and are pressed perpendicularly into a light and loose soil—half sharp sand and half leaf-mould—for nearly or quite their entire length, or are scattered in damp moss. Keep the soil simply moist, and for hardy and half-hardy species keep the temperature rather low—from 45° to 60°. Slight bottom heat may sometimes be given to advantage. In from three to ten weeks a little bulbel, or sometimes two or more, will appear at the base of the scale, as shown in [Fig. 15].

Fig. 15. Bulb-Scale.

These pots or flats may be plunged out-doors during summer if the planting was done in winter, or the scales may be potted off or transferred to the open border as soon as rootlets have formed. It is the common practice with most hardy species to allow the scales to remain in the original flats during summer and to cover them the next fall, allowing them to remain out-doors over winter. The succeeding spring they are shifted into a bed or border, and by the next fall—having had two summers' growth—most species will be ready for permanent planting in the flower border.

A bulblet is a small bulb borne entirely above ground, usually in the axil of a leaf or in the inflorescence. Familiar examples occur in the tiger lily and in “top” onions. In the former instance the bulblets are direct transformations of buds, while in the onion they are transformed flowers. It is impossible to draw any line of separation between bulblets and buds. In some plants, certain buds detach themselves and fall to the ground to multiply the species. Sometimes these buds vegetate before they fall from the plants, as in the case of various ferns. For purposes of propagation, bulblets are treated in the same way as bulbels, and like them, they reproduce the variety upon which they grow. They will develop into full grown bulbs in from one to three years, according to the species.

Fig. 16. Gladiolus Corm.

A corm is a bulb-like organ which is solid throughout. Familiar examples occur in the gladiolus and crocus. Cormous plants are multiplied in essentially the same manner as bulbous species. As a rule, a new corm is produced each year above the old one, and this commonly bears flowers the following season. This renewal is well shown in the gladiolus, [Fig. 16]. The illustration shows a gladiolus bottom, half size, when taken up in November. At the base are seen the withered remains of the corm which was planted in the spring, and above it the new corm which will furnish bloom the following season. A number of cormels or “spawn” have also appeared. These may be planted out in a border or bed and will produce mature bulbs in one or two seasons. The larger ones, under good treatment, will often produce bulbs an inch in diameter the first season. Some growers keep the cormels a year and a half before planting them out, as they are thought to vegetate more evenly under such treatment; in this case they should be placed in sand to prevent too great drying out.

Adventitious cormels may be produced by various methods of wounding the mother corm, and this practice of exciting them is often necessary, as some varieties do not produce cormels freely. Each bud on the top or side of the corm may be made to produce a separate corm by cutting a deep ring around it, so as to partly divide it. Or the corm may be directly cut into as many separate pieces as there are buds or eyes, after the manner of cutting potatoes, but these pieces are usually handled in flats where temperature and moisture can be controlled. Almost any injury to such vigorous corms as those of the gladiolus and crocus will result in the production of cormels, if care is taken that the corms do not become so cold and wet that they will rot.

A tuber is a prominently thickened portion of a root or stem, and it is usually subterranean. The potato, sweet potato and dahlia furnish good examples. Tuberiferous plants are multiplied by planting these tubers whole, or the tubers may be cut into small portions as described in [Chapter IV], in the descriptions of cuttings. In hardy species, the tubers may be allowed to remain in the ground during winter, but they are generally dug in the fall and stored in a dry and cold place, but where they will not freeze.

An offset is a crown or rosette of leaves, usually borne next the surface of the ground, which detaches itself and forms an independent plant. The best examples occur in the house-leeks, plants which are more familiarly known as “hen and chickens” and “man and wife.” These offsets take root readily, and in propagating there is no other care necessary than to remove and plant them.

A crown is a detachable portion of a root-stock bearing roots and a prominent bud. Rhizomes or root-stocks multiply individuals and extend the distribution of the species by means of a progressive movement of the crowns. The root-stock grows during summer, and at the end of the season each branch develops a strong terminal bud which usually produces a flowering stem the following season. The root-stock gradually dies away at its old extremity, and in a few years a single individual gives rise to a considerable patch. This is well shown by the common May-Apple or podophyllum.

Fig. 17. Lily of the Valley Crown.

In some species these crowns are removed in the autumn and are planted and handled in much the same manner as bulbs. The crown or pip of the lily of the valley, shown half size in [Fig. 17], is obtained in this manner.

[CHAPTER III.]

LAYERAGE.

Layerage.—The operation or practice of making a layer, or the state or condition of being layered.

Layer.—A shoot or root, attached to the parent plant, partially or wholly covered with earth with the intention that it shall take root and then be severed from the parent.

Stolon.—A decumbent shoot which, without the aid of man, takes root and forms an independent plant.

Many plants habitually propagate by means of decumbent shoots and runners. These shoots become more or less covered with earth or leaves, and roots are emitted, usually at the joints. In many cases, the old shoots die away and an entirely independent plant arises from each mass of roots. In other plants, the shoots remain attached to the parent, at least for a number of years, so that the plant comprises a colony of essentially distinct individuals. Great numbers of plants which do not propagate naturally by means of layers are readily increased by this means under the direction of the grower. In most cases it is only necessary to lay down the branches, cover them with earth, and allow them to remain until roots are well formed, when they can be severed from the parent. Layering is one of the simplest methods of propagation, as the mother plants nurse the layer plants until they can sustain themselves. It is a ready means of multiplying hard-wooded plants which do not grow well from cuttings.

All vines, and all plants which have runners or long and slender shoots which fall to the ground, may be multiplied readily by layerage. Among fruits, the black-cap raspberry is a familiar example. The canes of the current year bend over late in summer and the tips strike the earth. If the tip is secured by a slight covering of earth, or if it finds lodgment in a mellow soil, roots are emitted and in the fall a strong bud or “crown” or “eye” is formed for next year’s growth. The parent cane is severed in the fall or spring, some four or six inches above the ground, and an independent plant, known as a “root-tip,” as shown in [Fig. 18], is obtained. In this instance, as in most others, it is immaterial at what point the parent stem is severed, except that a short portion of it serves as a handle in carrying the plant, and also marks the position of the plant when it is set. The black raspberry propagates itself naturally by means of layers, and it is only necessary, in most cases, to bring the soil into a mellow condition when the tips begin to touch the ground in order that they may find anchorage. This layering by inserting the growing point has the advantage of producing very strong “crowns” or plants in autumn from shoots or canes of the same year, and it should be more generally practised. Even currants, gooseberries, and many other plants can be handled in this way.

Fig. 18. Raspberry tip.

Fig. 19. Covered Layer of Viburnum.

In most cases of layerage it is necessary to lay down the branches and to cover them. The covering may be continuous, as in [Fig. 19], or it may be applied only to the joints or restricted portions of the shoot, as illustrated in [Fig. 20]. In either case, the covering should be shallow, not exceeding one to three inches. If the shoot is stiff a stone or sod may be placed upon it to hold it down; or a crotched stick may be thrust down over it, as in the “pegging down” of propagators.

Fig. 20. Layered Shoots.

The strongest plants are usually obtained by securing only one plant from a shoot, and for this purpose the earth should be applied only at one point, preferably over a bud somewhere near the middle of the shoot. If the buds are close together, all but the strongest one may be cut out. If more plants are desired, however, serpentine layering may be practiced, as shown at A in [Fig. 20]. The shoot is bent in an undulating fashion, and from every covered portion roots will form and a plant may be obtained. The covered layer also possesses the advantage of giving more than one plant, but the roots are apt to form so continuously that definite and strong plants are rarely obtained; these rooted portions may be treated as cuttings, however, with good results. The grape is sometimes propagated by serpentine layering.

Stiff and hard-wooded plants do not often “strike” or root readily, and in order to facilitate rooting the branch is wounded at the point where a new plant is desired. This wounding serves to induce formation of adventitious buds at that point, and to check the growth of the branch at the tip. It is a common practice to cut the branch about half in two obliquely, on the lower side. This operation is known as “tongueing.” "Ringing" or girdling, twisting, notching, and various other methods are employed, none of which, perhaps, possess any peculiar advantages in general practice. Some propagators cut all the buds from the covered portion. In this case the free and protruding end of the layer is expected to form the top of the new plant. “Arching,” or very abrupt bending, as in serpentine layering, serves the same purpose and is the only attention necessary in most vines.

When large numbers of plants are desired, as in commercial nurseries, it is often necessary to cut back the parent plant to the ground, or very nearly so, for the purpose of securing many shoots fit for layering. A plant which is cut back in the spring will produce shoots fit for layering the following spring; or some species will produce them in abundance the same year if layers of green or immature wood are desired. These parent or stock-plants are called “stools” by nurserymen.

Fig. 21. Mound Layering of Gooseberry.

In many species layerage is performed to best advantage by heaping earth over the stool and around the shoots. This is known as mound or stool layering. The shoots send out roots near the base and straight, stocky plants are obtained. The English gooseberries are almost exclusively propagated in this manner in this country. [Fig. 21] shows a row of mound-layered gooseberries. The shoots are allowed to remain in layerage two years, in the case of English gooseberries, if the best plants are wanted, but in many species the operation is completed in a single season. Quinces and Paradise apple stocks are extensively mound-layered. The practice is most useful in those low plants which produce short and rather stiff shoots.

As a rule, the best season for making layers is in spring when the leaves are forming. Rooting progresses rapidly at that season. Many plants “bleed” if layered earlier in the season. Hardy shrubs may be layered in the fall, either early or late, and if an incision is made, a callus will have formed by spring. If rapid multiplication is desired, the soft and growing shoots may be layered during the summer. This operation is variously known as “summer,” "herbaceous," “green” and “soft” layering. Comparatively feeble plants usually result from this practice, and it is not in common favor.

Fig. 22. Pot layerage.

Pot layering, circumposition, air layering and Chinese layering are terms applied to the rooting of rigid stems by means of surrounding them, while in their natural position, by earth or moss, or similar material. The stem is wounded—commonly girdled—and a divided pot or box is placed about it and filled with earth ([Fig. 22]). The roots start from above the girdle, and when they have filled the pot the stem is severed, headed back, and planted. Pot layering is practiced almost exclusively in greenhouses, where it is possible to keep the earth uniformly moist. But even there it is advisable to wrap the pot in moss to check evaporation from the soil. Some plants can be readily rooted by wrapping them with moss alone. Pot layering is employed not only for the purpose of multiplying plants, but in order to lower the heads of “leggy” or scraggly specimens. The pot is inserted at the required point upon the main stem, and after roots have formed abundantly the top may be cut off and potted independently, the old stump being discarded.

Fig. 27. Compound layering pot.

The French have various handy devices for facilitating pot layering. [Fig. 23] shows a layering pot, provided with a niche in the side to receive the stem, and a flange behind for securing if to a support. [Fig. 24] represents a layering cone. It is made of zinc or other metal, usually four or five inches high, and is composed of two semi-circular wings which are hinged on the back and are secured in front, when the instrument is closed, by means of a hinge-pin. A cord is inserted in one side with which to hang it on a support. A cup or pot with a removable side is also used. This is shown open in [Fig. 25] and closed in [Fig. 26]. An ingenious compound layering pot is shown in [Fig. 27]. The main stem or trunk of the plant is carried through the large opening, and the branches are taken through the smaller pots at the side. Kier’s layering boxes or racks are shown in Figs. [28] and [29]. The trays are filled with earth and the branches are laid in through the chinks in the border and are treated in the same manner as ordinary out-door layers. These racks supply a neat and convenient means of increasing greenhouse plants which do not readily strike from cuttings.

It is well to bear in mind that when layers do not give strong plants, they can be divided into portions and treated as ordinary cuttings. This is an important operation in the case of rare varieties which are multiplied by means of soft or green layers, as some of the large-flowered clematises and grapes. The weak small plants are handled in a cool greenhouse or under frames, usually in pots, and they soon make strong individuals.

[CHAPTER IV.]

CUTTAGE.

Cuttage.—The practice or process of multiplying plants by means of cuttings, or the state or condition of being thus propagated.

Cutting.—A severed portion of a plant, inserted in soil or water with the intention that it shall grow; a slip.

Cuttings, particularly of growing parts, demand a moist and uniform atmosphere, a porous soil and sometimes bottom heat.

Fig. 32. Propagating-box.

Devices for Regulating Moisture and Heat.—In order to secure a uniform and moist atmosphere, various propagating-frames are devised. Whatever its construction, the frame should be sufficiently tight to confine the air closely, it should admit light, and allow of ventilation. The simplest form of propagating-frame is a pot or box covered with a pane of glass. To admit of ventilation the glass is tilted at intervals, or two panes may be used and a space be allowed to remain between them. A common bell-glass or bell-jar (cloche of the French) makes one of the best and handiest propagating-frames because it admits light upon all sides and is convenient to handle. These are in universal use for all difficult and rare subjects which are not propagated in large numbers. A hand-glass or hand-light ([Fig. 30]) answers the same purpose and accommodates a larger number of plants. A useful propagating-box for the window garden or amateur conservatory is shown in [Fig. 31]. A box two or three inches high is secured, and inside this a zinc or galvanized iron tray, a, is set, leaving sufficient space between it and the box to admit a pane of glass upon every side. These panes form the four sides of the box, and one or two panes are laid across the top. The metal tray holds the soil and allows no water to drip upon the floor. One of the best boxes for general purposes is made in the form of a simple board box without top or bottom, and fifteen or eighteen inches high, the top being covered with two sashes, one of which raises upon a hinge ([Fig. 32]). Four by three feet is a convenient size. An ordinary light hot-bed frame is sometimes constructed upon the bench of a greenhouse and covered with common hot-bed sash. Propagating houses are sometimes built with permanent propagating-frames of this character throughout their length.

Fig. 33. Simple Propagating-oven.

Fig. 34. Propagating-oven.

In all the above appliances heat is obtained from the sun or from the bench-pipes or flues of a greenhouse. There are various contrivances in which the heat is applied locally, for the purpose of securing greater or more uniform heat. One of the simplest and best of these is the propagating-oven shown in [Fig. 33]. It is a glass covered box about two feet deep, with a tray of water beneath the soil, and which is heated by a lamp. A similar but somewhat complicated apparatus is illustrated in Figs. [34], [35], [36]. This is an old form of oven, which has been variously modified by different operators. [Fig. 34] shows a sectional view of the complete apparatus. The box, A A, is made of wood and is usually about three feet square. L is a removable glass top. B represents a zinc or galvanized iron tray which is filled with earth in which seeds are sown or pots are plunged. C is a water tray to which the water is applied by means of a funnel extending through the box. A lamp, D, supplies the heat. A funnel of tin, e e, distributes the heat evenly. Holes should be provided about the bottom of the box to admit air to the flame. A modified form of this device is shown in Figs. [35] and [36]. The water tray, G, slides in upon ledges so that it can be removed, and the heat funnel, L D L, slides in similarly and is made to surround the flame like a chimney. The front side of the apparatus is removable, and the top of the frame, K, is made of metal. The cover for this apparatus is figured in [Fig. 36]. The ends, a a, are made of wood, with openings, indicated by the arrows, to allow of ventilation. The front and top, g g, are made of glass. The frame-work, c c c, is made of metal. The cover is hinged on, or held with pegs, I I, [Fig. 35].

Fig. 35. Modified form of [Fig. 34].

Fig. 36. Cover for [Fig. 35].

Chauvière’s propagating-frame, an apparatus used by the French, is shown in [Fig. 37]. It is essentially a miniature greenhouse. The sashes are seen at c c, and above them is a cloth or matting screen. The sides below the sashes are enclosed, preferably with glass. The bottom or floor is moveable, and it is sometimes divided into two or three sections to allow for the accommodation of plants of different sizes and requirements. These sections are raised or lowered and are held by pegs. At a is shown a section of floor elevated, and at the left another section occupying a lower position. Heat is supplied usually by hot water in the tubes, d d. A very elaborate circular French device, known as Lecoq’s propagating-oven, is illustrated in [Fig. 38]. It is an interesting apparatus, and is worth attention as showing the care which has been taken to control the conditions of vegetation and germination. It is too elaborate for common purposes, and yet for the growing of certain rare or difficult subjects it might find favor among those who like to experiment; and it affords an accurate means of studying plant growth under control. The apparatus is sold in France for about $6. All the portion below the glass top, P p, is made of earthenware. The base, a a, holds a lamp, d; e is a water reservoir to which water is supplied by means of the funnel, j. A vase or rim, b b, rests upon the base, and upon it a plate or disc, c c, is fitted. Above this is a glass top, P p. Air is admitted to the apparatus at i, K K, and between the vase and plate, as at c on the right. The plate contains two circular grooves, g g and h h. In these grooves the soil is placed or pots plunged. The heat circulates in the valleys m and n n n n, and supplies a uniform temperature to both sides of the plants.

Fig. 37. Chauvière’s Propagating-oven.

Fig. 38. Lecoq’s Propagating-oven.

Fig. 39. Barnard’s Propagating-tank.

Barnard’s propagating-tank, [Fig. 39], is a practicable device for attachment to a common stove. A similar apparatus may be attached to the pipes of a greenhouse. The tank consists of a long wooden box made of matched boards, and put together with paint between the joints to make the box water-tight. The box should be about three feet wide and ten inches deep, and may be from ten to thirty feet long, according to the space required. In the middle of the box is a partition, extending nearly the whole length of the box, and on the inside, on each side, is a ledge or piece of moulding to support slates to be laid over the entire surface of the box. The slates are supported by the ledges and by the central partition, and should be fastened down with cement to prevent the propagating sand from falling into the tank. One slate is left out near the end, next the fire, to enable the operator to see the water and to keep it at the right level. On the slates sand is spread, in which the cuttings may be struck, the sand nearly filling the box. At one end of the box is placed a common cylinder stove, with pipe to the chimney. Inside the stove is a lead or iron pipe (iron is the best) bent in a spiral. This coil, which is directly in the fire, is connected by iron pipes with the tank, one pipe leading to one side of the partition and the other to the opposite side, as shown in the drawing. If water is placed in the tank it will fill the pipes and form a continuous circulating system through the pipes and up one side of the box past the end of the partition, and down the other side. A fire in the stove causes the water to circulate through the tank and impart to the bed a genial warmth.

Fig. 40. Zinc Propagating-tank.

There are various tanks designed to rest upon the pipes in a greenhouse. The principle of their construction is essentially the same as of those described in previous pages—bottom heat, a tray of water, and a bed of soil. Earthenware tanks are commonly employed, but a recent English device, [Fig. 40], is made of zinc. It is about seven inches deep, and holds an inch or two of water in the bottom. A tray five inches deep sets into the tank. The water is supplied through a funnel at the base.

Cuttings usually “strike” better when they touch the side of the pot than when they are wholly surrounded by soil. This is because the earthenware allows greater uniformity in moisture than the earth, and supplies air and a mild bottom heat. Various devices are employed for the purpose of securing these advantages to the best effect. These are usually double pots, in one of which water is placed. A good method is that represented in [Fig. 41], which shows a pot, b, plugged with plaster of Paris at the bottom, placed inside a larger one. The earth is placed between the two, drainage material occupying the bottom, a, and fine soil the top, c. Water stands in the inner pot as high as the dotted line and feeds uniformly into the surrounding soil. The positions of the water and soil are frequently reversed, but in that case there is less space available for cuttings. Neumann’s cutting-pot is shown in [Fig. 42]. This contains an inverted pot in the center, a, designed to supply drainage and to admit heat into the center of the mass of soil.

Fig. 41. Forsyth’s Cutting-pot.

Some kind of protection, commonly combined with bottom heat, is always given cuttings made from the soft and growing parts. In in-door work, any of the devices named above may be employed, but a box like that shown in [Fig. 32] is one of the most useful for common operations. Or the greenhouse itself may afford sufficient protection, especially if the cuttings are shaded when first set to check evaporation from the plant and soil, and to prevent too great heat. This shading is usually supplied by whitewashing the glass, or a newspaper may be laid over the cutting bed for a few days. A greenhouse table or bench prepared for the growing of cuttings is known as a “cutting bench.” If the cuttings become too dry or too hot, they will wilt or “flag.” In out-door work soft cuttings are usually placed in an ordinary cold-frame, and these frames must be shaded. They may be placed under trees or on the shady side of a building, or if they are numerous, as in commercial establishments, a cloth screen should be provided as shown in [Fig. 5], [page 13].

Fig. 42. Neumann’s Cutting-pot.

Soils and General Methods.—Soil for all cuttings should be well-drained. It should not be so compact as to hold a great quantity of water, nor should it be so loose as to dry out very quickly. It should not “bake” or form a crust on its surface. As a rule, especially for cuttings made of growing parts, the soil should not contain vegetable matter, as such material holds too much water and it is often directly injurious to the cutting. A coarse sharp, clean sand is the best material for use in-doors. Very fine sand packs too hard, and should not be used. Some propagators prefer to use fine gravel, composed of particles from an eighth to a fourth of an inch in diameter, and from which all fine material has been washed. This answers well for green cuttings if a propagating-frame is used to check evaporation and attention is given to watering, because drainage is so perfect and the material so quickly permeable that uniformity of treatment is secured. Damping-off is less liable to occur in such material than in denser soils. The same advantages are to some extent present in sphagnum moss and cocoanut fibre, both of which are sometimes used in place of earth. The “silver sand” used by florists is a very clean and white sand which derives its particular advantages from the almost entire absence of any vegetable matter. But it is not now considered so essential to successful propagation as it was formerly, and fully as good material may often be found in a common sand-bank. Cuttings which strike strongly and vigorously may be placed in a soil made of light garden loam with twice its bulk of sand added to it. All soils used for in-door cuttage should be sifted or screened before using to bring them to a uniform texture.

Hard-wood cuttings are commonly planted out-doors in mellow and light loam, well trenched. Only fine and well-rotted manure should be applied to the cutting bed, and it should be well mixed with the soil. In most cases, a well-drained soil gives best results, but some cuttings root and grow well in wet soils or even in standing water, as poplars, willows, some of the dogwoods, plane-tree and others.

Bottom heat is always essential to the best success with cuttings. In out-door work this is supplied by the natural heat of the soil in spring and summer, and it is often intensified by burying hard-wooded cuttings bottom end up for a time before planting them. This operation of inverting cuttings is often practiced with grapes, particularly with the Delaware and others which root with some difficulty. The cuttings are tied in bundles and are buried in a sandy place, with the tops down, the butts being covered two or three inches with sand. They may be put in this position in the fall and allowed to remain until the ground begins to freeze hard, or they may be buried in spring and allowed to remain until May or June and then be regularly planted. In out-door cuttage, the cuttings which are of medium length, from six to eight inches, derive more bottom heat than the very long ones, such as were formerly used for the propagation of the grape. In in-door work bottom heat is obtained artificially. Cutting benches should have abundant piping beneath, and in the case of many tropical and sub-tropical species the bottom heat may be intensified by enclosing the benches below so that no heat can escape into the house. Doors can be placed in the partition alongside the walk to serve as ventilators if the heat should become too intense. In all cuttings, bottom or root growth should precede top growth, and this is aided by bottom heat.

Fig. 43. Grape cutting.

As a rule, roots arise most readily from a joint, and it is therefore a common practice to cut off the base of the cutting just below a bud, as shown in the grape cutting, [Fig. 43]. Sometimes the cutting is severed at its point of attachment to the parent branch, and a small portion, or “heel,” of that branch is allowed to remain on the cutting. This heel may be nothing more than the curved and hardened base of the cutting at its point of attachment, as in the cornus cutting, [Fig. 44]. Sometimes an entire section of the parent branch is removed with the cutting, as in the “mallet” cuttings of grapes, [Fig. 45]. Of course, comparatively few heel or mallet cuttings can be made from a plant, as only one cutting is obtained from a branch, and it is advisable, therefore, to “cut to buds” rather than “cut to heels;” yet there are many plants which demand a heel, if satisfactory results are to be obtained. The requirements of the different species in this direction can be learned only by experience, but it may be said that in general the hardest or closest wooded plants require a heel or a joint at the base. Willows, currants, basswoods, and others with like soft wood, emit roots readily between the buds, yet even in these cases propagators quite usually cut to buds.

Fig. 44. Heel cutting of Cornus.

Wounds upon plants begin to heal by the formation of loose cellular matter which gives rise to a mass of tissue known as a callus. This tissue eventually covers the entire wound, if complete healing results. As a rule, the first apparent change in a cutting is the formation of a callus upon the lower end, and it is commonly supposed that this process must be well progressed before roots can form. But roots do not necessarily arise from the callus, and in many plants they appear to bear no relation to it in position. In willows, for instance, roots arise from the bark quite irregularly and at some distance from the callus. Yet, as a matter of practice, best results are obtained from callused cuttings, particularly if the cuttings are made from mature wood, but this is probably due quite as much to the fact that considerable time is required for the formation of the adventitious buds which give rise to the roots as from any connection between the callusing and rooting processes themselves. Hard-wood cuttings give better results when kept dormant for some time after they are cut. They are usually made in the fall, and stored during the winter in sand, sawdust or moss in a cool cellar, or buried in a sandy and well-drained place. This, at least, is the practice with hard-wood cuttings of deciduous plants. Hard-wood evergreen cuttings, when taken in the fall, are usually set at once, as their foliage will not allow them to be buried with safety; but in this case, the cuttings are kept “quiet” or dormant for a time, to allow callusing to progress. If cuttings are buried so deep that they cannot sprout, callusing may be hastened by placing them in a mild temperature. Single-eye grape cuttings are sometimes packed between layers of sand in a barrel and the barrel is set under a forcing-house bench where the temperature is about 50°. Eight or ten inches of sand is usually placed over the top layer. In this manner, cuttings which have been obtained in winter or spring can be callused before planting time.

Fig. 45. Mallet cutting of grape.

It is a singular fact that the lower end of the cutting, as it stood upon the parent plant, produces roots and the upper end produces leaves and shoots, even if the cutting is inverted. And if the cutting is divided into several parts, each part will still exhibit this same differentiation of function. This is true even of root-cuttings, and of other cuttings which possess no buds. The reasons for this localization of function are not yet clearly understood, although the phenomenon has lately been the subject of study. Upon this fact depends the hastening of the rooting process in inverted cuttings by the direct application of heat to the bottoms, and it likewise indicates that care must be taken to plant cuttings in approximately their natural direction if straight and handsome plants are desired.

The particular method of making the cutting and the treatment to which it should be subjected, must be determined for each species or genus. Some plants, as many maples, can be propagated from wood two or three years old, but in most cases the wood of the previous or present season’s growth is required. Nearly all soft and loose wooded plants grow readily from hard-wood cuttings, while those with dense wood are often multiplied more easily from soft or growing wood. Some plants, as oaks and hickories, are propagated from cuttings of any description only with great difficulty. It is probable, however, that all plants can be multiplied by cuttings if properly treated. It often happens that one or two species of a closely defined genus will propagate readily from cuttings while the other species will not, so that the propagator comes to learn by experience that different treatment is profitable for very closely related plants. For instance, most of the viburnums are propagated from layers in commercial establishments, but V. plicatum is grown extensively from cuttings.

Particular Methods—Kinds of Cuttings.—Cuttings are made from all parts of the plant. In its lowest terms, cuttage is a division of the plant itself into two or more nearly equal parts, as in the division of crowns of rhubarb, dicentra, and most other plants which tend to form broad masses or stools. This species of cuttage is at times indistinguishable from separation, as in the dividing of lily bulbs ([page 25]), and at other times it is essentially the same as layerage, as in the dividing of stools which have arisen from suckers or layers. This breaking or cutting up of the plants into two or more large parts which are already rooted is technically known as division. It is only necessary, in dividing plants, to see that one or more buds or shoots remain upon the portions, and these portions are then treated in the same manner as independent mature plants; or sometimes, when the divisions are small and weak, they may be handled for a time in a frame or forcing-house in the same manner as ordinary cuttings.

Cuttings proper may be divided into four general classes: 1, of tubers; 2, of roots and root-stocks; 3, of stems; 4, of leaves.

1. Tuber Cuttings.—Tubers are thickened portions of either roots or stems, and tuber cuttings therefore fall logically under classes 2 and 3; but they are so unlike ordinary cuttings that a separate classification is desirable. Tubers are stored with starch, which is designed to support or supply the plant in time of need. Tuber cuttings are therefore able to support themselves for a time if they are placed in conditions suited to their vegetation. Roots rarely arise from the tubers themselves, but from the base of the young shoots which spring from them. This fact is familiarly illustrated in the cuttings of Irish and sweet potatoes. The young sprouts can be removed and planted separately and others will arise from the tuber to take their places. This practice is employed sometimes with new or scarce varieties of the Irish potato, and three or four crops of rooted sprouts can be obtained from one tuber. The tuber is cut in two lengthwise and is then laid in damp moss or loose earth with the cut surface down, and as soon as the sprouts throw out roots sufficient to maintain them they are severed and potted off. Sweet potatoes are nearly always propagated in this manner.

In making tuber cuttings, at least one eye or bud is left to each piece, if eyes are present; but in root-tubers, like the sweet potato, there are no buds, and it is only necessary to leave upon each portion a piece of the epidermis from which adventitious buds may develop. The pseudo-bulbs of some orchids are treated in this manner, or the whole bulb is sometimes planted. A shoot, usually termed an off-shoot, arises from each pseudo-bulb or each piece of it, and this is potted off as an independent plant. (See [Orchids], in [Chapter VI].)

Cuttings made from the ordinary stems of some tuberiferous plants will produce tubers instead of plants. This is the case sometimes with the potato. The cutting produces a small tuber near its lower extremity, or sometimes in the axil of a leaf above ground, and this tuber must be planted to secure a new plant. Leaf cuttings of some tuberiferous or bulbiferous plants produce little tubers or bulbs in the same way. Hyacinth leaves, inserted in sand in a frame, will soon produce little bulblets at their base, and these can be removed and planted in the same manner as the bulbels described in [Chapter II].

Many tubers or tuber-like portions, which possess a very moist or soft interior and a hard or close covering, vegetate more satisfactorily if allowed to dry for a time before planting. The pseudo-bulbs of orchids, crowns of pine-apples and cuttings of cactuses are examples. Portions of cactuses and pine-apples are sometimes allowed to lie in the sun from two to four weeks before planting. This treatment dissipates the excessive moisture and induces the formation of adventitious buds.

Fig. 46. Root-cutting of Blackberry.

Fig. 47. Root-cutting of Dracæna.

2. Root Cuttings.—Many plants can be multiplied with ease by means of short cuttings of the roots, particularly all species which posses a natural tendency to “sucker” or send up sprouts from the root. All root-stocks or underground stems can be made into cuttings. True root cuttings possess no buds whatever; the buds develop after the cutting is planted. Roots are cut into pieces from one to three inches long and are planted horizontally in soil or moss. These cuttings thrive best with bottom heat, but blackberries and some other plants, grow readily with ordinary out-door treatment. A root-cutting of the blackberry is shown in [Fig. 46]. (See [Blackberry], in [Chapter VI].) A growing dracæna cutting is exhibited in [Fig. 47]. The cuttings of this plant are handled in a propagating-frame or on a cutting bench in a warm greenhouse. The bouvardias and many other plants can be grown in the same manner. Many of the fruit-trees, as peach, cherry, apple and pear, can be grown readily from these short root-cuttings in a frame. Variegation cannot always be transmitted by root-cutting, e. g., Symphytum asperrimum, variegatum. Among kitchen garden plants, the horse-radish is the most familiar example of propagation by root-cuttings. The small side roots, a fourth inch or so in diameter, are removed when the horse-radish is dug in fall or spring, and are cut into four to six inch lengths, as seen in [Fig. 48]. These cuttings are known as “sets” among gardeners. (See [Horse-radish], [Chapter VI].) When the crowns of horse-radish are cut and used for propagation, the operation falls strictly under division, from the fact that buds or eyes are present; and the same remark applies to rhubarb, which, however, is not propagated by true root-cuttings.

Fig. 48. Horse-radish root-cuttings.

3. Stem Cuttings.—Cuttings of the stem divide themselves into two general classes: those known as cutting of the ripe, mature or hard wood, and cuttings of the green, immature or soft wood. The two classes run into each other; no hard and fast lines can be drawn.

Hard-wood cuttings are made at any time from late summer to spring. It is advisable to make them in the fall in order to allow them to callus before the planting season, and to forestall injury which might result to the parent plant from a severe winter. They may be taken as early as August, or as soon as the wood is mature, and be stripped of leaves. Callusing can then take place in time to allow of fall planting. Or the cuttings taken in early fall may be planted immediately and be allowed to callus where they stand. All fall cutting beds should be mulched to prevent the heaving of the cuttings. As a rule, however, hard-wood cuttings are buried on a sandy knoll or are stored in moss, sand or sawdust in a cellar until spring. (See [page 50].)

There is no general rule to govern the length of hard-wood cuttings. Most propagators prefer to make them six to ten inches long, as this is a convenient length to handle. Two buds are always to be taken, one bud or one pair at the top and also at the bottom, but in “short-jointed” plants more are obtained. Sometimes all but the top buds are removed to prevent the appearance of too many shoots. Grape cuttings are now commonly cut to two or three buds ([Fig. 43]), two being the favorite number for most varieties. (See [Grape], [Chapter VI].) Currant and gooseberry cuttings ([Fig. 49]) usually bear from six to ten buds. All long hard-wood cuttings are set perpendicularly, or nearly so, and only one or two buds are allowed to stand above the surface.

Fig. 49. Currant cutting.

When the stock is rare, cuttings are made of single eyes or buds. This is particularly the case with the grape (see [Chapter VI]), and currants and many other plants are occasionally grown in the same manner. [Fig. 50] shows a single eye grape cutting. These cuttings, whatever the species, are commonly started under glass with bottom heat, either upon a cutting bench or in a hot-bed. The soil should be kept uniformly moist, and when the leaves appear the plants should be frequently sprinkled. In from thirty to forty days the plants are ready to pot off. Single eye cuttings are usually started about three or four months before the season is fit for out-door planting, or about February in the northern states. The most advisable method of treatment varies with the season and locality as well as with the species or variety. It is well known, for instance, that the Delaware grape can be propagated more easily in some regions than in others. A common style of single eye cutting is made with the eye close to the top end, and a naked base of an inch or two. This is inserted into the soil perpendicularly, with the eye just above the surface. It is much used for a variety of plants.

Fig. 50. Single-eye Grape cutting.

Many coniferous plants are increased by cuttings on a large scale, especially retinosporas, arbor-vitæs, and the like. Cuttings are made of the mature wood, which is planted at once (in autumn) in sand under cover, usually in a cool greenhouse. Most of the species root slowly and they often remain in the original flats or benches a year, but their treatment is usually simple. In some cases junipers, yews and Cryptomeria Japonica will not make roots for nearly twelve months, keeping in good foliage however, and ultimately giving good plants. (For more explicit directions, see Thuya and Retinospora in [Chapter VI].)

Most remarkable instances of propagation by means of portions of stems are on record. Chips from a tree trunk have been known to produce plants, and the olive is readily increased by knots or excrescences formed upon the trunks of old trees. These excrescences occur in many plants and are known as knaurs. They are often abundant about the base of large plane-trees. But they are not often used for purposes of propagation. Whole trunks will sometimes grow after having been cut for many months, especially of such plants as cactuses, many euphorbias and yuccas. And sections of these spongy trunks will grow, also. Even saw-logs of our common trees, as elm and ash, will sprout while in the “boom,” or water.

Green-wood cuttings are more commonly employed than those from the mature wood, as they “strike” more quickly, they can be handled under glass in the winter, and more species can be propagated by them than by hard-wood cuttings. “Slips” are green-wooded cuttings, but the term is often restricted to designate those which are made by pulling or “slipping” off a small side shoot. All soft-wooded plants and many ornamental shrubs are increased by green cuttings. There are two general classes of green-wood cuttings: those made from the soft and still growing wood, and those made from the nearly ripened green-wood, as in Azalea Indica, oleander, ficus, etc. House plants, as geraniums, coleuses, carnations, fuchsias, and the like, are grown from the soft young wood, and many harder-wooded plants are grown in the same way. Sometimes truly hard wood is used, as in camellia.

Fig. 51. Tough and brittle wood.

In making cuttings from soft and growing shoots, the first thing to learn is the proper texture or age of shoot. A very soft and flabby cutting does not grow readily, or if it does it is particularly liable to damp-off, and it usually makes a weak plant. Too old wood is slow to root, makes a poor plant and is handled with difficulty in many species. The ordinary test for beginners is the manner in which the shoot breaks. If, upon being bent, the shoot snaps off squarely so as to hang together with only a bit of bark, as in the upper break in [Fig. 51], it is in the proper condition for cuttings; but if it bends or simply crushes, as in the lower portion of the figure, it is either too old or too young for good results. The tips of the shoots of soft-wooded plants are usually employed, and all or a portion of the leaves are allowed to remain. They are inserted in sharp sand to a sufficient depth to hold them in place, and the atmosphere and soil must be kept moist to prevent wilting or "flagging". The cuttings should also be shaded for the first week or two. A propagating-frame is often employed. Soft cuttings are commonly cut below a bud or cut to a heel, but this is unnecessary in easily rooted plants like geranium, coleus, heliotrope, etc. [Fig. 52] shows an oleander cutting at a, a carnation at b, and a geranium at c. A coleus cutting is illustrated in [Fig. 53]. Sometimes the growth is so short or the stock so scarce that the cutting cannot be made long enough to hold itself in the soil. In such case a toothpick or splinter is tied to the cutting to hold it erect, as in the cactus cutting, [Fig. 54], or the geranium cutting, [Fig. 55]. In the window garden, soft cuttings may be started in a deep plate which is filled half or two-thirds full of sand and is then filled to the brim with water, and not shaded; this method, practiced on a larger scale, is sometimes useful during the hot summer months. If bottom heat is desired, the plate may be set upon the back part of the kitchen stove. Oleanders usually root best when mature shoots are placed in bottles of water.

Fig. 52. Soft cuttings.