|Standard Cyclopedia of Horticulture|
Cuttings, propagation by. A cutting is the gardener's name for a piece of stem, root, rootstock or leaf, which, if cut off and planted under suitable conditions, will form new roots and buds, reproducing the parent plant.
The word cutting, when unrestricted, is given to parts of the stem; a part or the whole of the leaf, when so used, is called a leaf-cutting; a piece of root or root- stock is called a root-cutting. The scales of some bulbous plants, as of the lily, can also be used as cuttings. A cion used in grafting might be called a cutting which unites and grows on another plant. Plants secured by division or layering are provided with roots before they are detached from the parent plants, and, therefore, are not properly cuttings. There are intermediate states between these different categories, however, so that hard-and-fast definitions do not hold.
The practice of propagating by means of cuttings, together with the discussion of the reasons, results and bearings, constitutes a department of horticultural knowledge that has been denominated cuttage, as the practices, reasons and philosophy of tilling have been called tillage.
Multiplication by cuttings is a form of bud-propagation in contradistinction to sexual reproduction, i.e., propagation by seeds. It. is a cheap and convenient way of securing new plants. All plants cannot be profitably increased by these means. Why they differ we do not know; the gardener learns by experience what species yield a good percentage of healthy plants, and acts accordingly. The following table will show the different ways in which cuttings are made: Soft e.g., verbena Growing wood Stem…….. Hardened e.g., tea roses. Long, in open air e.g., grape Ripened wood Short, under glass e.g., Japanese cedar Cuttings Short, under glass e.g., Anemone japonica. Roots or rootstocks Long, in open-air e. g., blackberry. Entire e.g., echeveria Leaf ……………. Divided e.g., Begonia Rex Bulb-scales e.g., lilies
There is less variation in cutting-progeny than in seed-progeny, and therefore cuttings (or layers or cions) are used when it is desired to keep a stock particularly true to name. They are used largely for the multiplication of forms that are specially variable from seed (which have not become fixed by seed selection), and of mutations as between the different branches or parts of a plant (bud sports). Thus, the varieties of roses, chrysanthemums, carnations, most begonias, and currants and grapes can be grown from cuttings. Cuttings are also employed when seeds are difficult to secure, as in many greenhouse plants, or when propagation by seeds is difficult and cuttings are easy, as in poplars and willows.
Under glass cuttings are commonly planted in pure sand, such as a mason would use for making mortar. Sphagnum moss is sometimes used and various substances like brick-dust, coal-ashes jadoo fiber have been tried, but without much success. Sand and well-rotted leaf-mold mixed half and half; is occasionally employed for geraniums, for lily scales, root-cuttings and some succulent plants.
Sphagnum is useful in rooting Ficus elastica, the base of the cutting being wrapped in a ball of moss and plunged in a bed of moss. English ivy, oleander and other plants can be struck in water, but this method is cumbersome. Peter Henderson's saucer method is valuable in hot weather: the cuttings are planted in sand, kept saturated and fully exposed to sun.
In the open air, a well-protected place, a part of the frame-yard, for example, should be chosen for a cutting-bed. The aspect should be southerly and the soil must be well drained. The soil should also be trenched to the depth of 2½ to 3 feet, all poor material removed and additions of humus, in the form of peat, leaf-mold or well-rotted barnyard manure incorporated. Provision for watering should be easy. If the soil is a heavy clay, add sand.
Structures in which cuttings are started. Figs. 1160-1165.
Large establishments have one or more houses set apart for this and similar purposes called "propagating-houses." In smaller places a propagating-bed or -bench can be made at the warmest end of the warmest house. It should be placed over the pipes where they leave the boiler, and, in order to secure bottom heat when needed, the space between the bench and the floor should be boarded up, having a trap-door to open on cold nights (Fig. 1160). Cutting-frames inside a greenhouse are also shown in Fig. 1161. Side partitions should also be provided to box in all the heat from the pipes under that part of the bench. Good dimensions for such a bed are, width 3 feet, length 6 feet or any multiple of six thus making it simple to use a hotbed sash when confined air is wanted. The depth of the frame should be from 6 to 10 inches in front and about the same behind. The bottom of the bed may be either wood, slate or metal and should be well drained: place a layer of potsherds first, then moss, and from 2 to 3 inches of sand on top. The sand should be clean, sharp and well compacted: before planting it should be watered if at all dry. It is sometimes advisable to have the bed filled with moss (sphagnum), into which pots or boxes containing cuttings are plunged: the moss should be moist, neither too wet nor dry, and well packed.
In many cases, when large quantities of one sort of easily struck cuttings are to be planted, the ordinary greenhouse bench covered with sand is sufficient (Fig. 1162).
Hand-lights and bell-flosses are sometimes used under glass for small quantities of cuttings instead of frames. They may be of every convenient size up to 12 or 15 inches in diameter. The important point is that provision for good ventilation be always provided: if too much water accumulates inside the glass it can be wiped off with a cloth. They are somewhat obsolete devices for providing a close atmosphere and intensifying bottom heat. The modern gardener finds that sunlight and shading with papers put directly over the cuttings is quite sufficient for all plants except a few difficult subjects. Figs. 1163-1165 illustrate forms of hand structures. Out-of-doors cold- frames are employed for striking cuttings in summer. They are made of concrete or plank, and are about 5H feet wide, 18 inches deep behind and 12 inches in front. They are of any convenient length, which is a multiple of three and are covered with standard hotbed sash. Instead of coldframes, light hotbeds are sometimes employed for rooting cuttings in the open air in summer. They entail more care and the results do not offset the gain.
Cuttings of growing wood. Figs. 1166-1171.
These cuttings are made either of the soft growing tips, as in coleus (Fig. 1166; also Fig. 1027, p. 827). salvia, verbena (Fig. 1167), geranium (Fig. 1168) and others, or, of the same wood in more mature condition, but by no means ripe, as in tender roses (Fig. 1169), and Azalea indica. The cuttings of plants like Euphorbia pulcherrima, erica, epacris, are used in the soft growing state, if a well-built propagating-house is obtainable; but in an ordinary house, a part of which is used for other purposes, the older and better ripened wood will be more successful.
It is generally true that cuttings of hardened wood will always root, although they require more time and may not make the best plants, but it is not true that cuttings of the soft wood will always root. In many cases, as in the rose, they succumb before they callus, much less produce roots. In plants of rapid growth and good vitality, the proper condition of the soft growing wood for cuttings can be determined by its readiness to snap, not bend, when bent back: the hardened wood is in the right state as long as it continues to grow.
The treatment of cuttings in both classes is practically the same. They should be planted in sand under glass.
The wood for soft cuttings should be fresh, and precautions should be taken to prevent wilting during making and planting: if the weather is hot, sprinkle the floor and bench of the workroom: if they are delicate and exposed for an hour or more, lay them between folds of moistened paper. The average length of these cuttings is from 1 to 3 inches, but they can be made longer or shorter; much depends upon the nature of the plant. The best growers prefer short cuttings; the advantage of a long piece to begin with is more than offset by greater danger of wilting and consequent retrogression. It is not necessary to cut to a bud, i. e., at the node, in the more easily handled plants except in some herbaceous tuberous- rooted plants, like dahlia (see Fig. 1170), and Salvia patens, in which a crown must be formed to insure future growth. Make the cut where it will give the proper length. A part of the leaves should be removed, always enough to secure a clean stem for planting, and as many more as are needed to prevent disastrous wilting: this factor varies greatly. In a hardwood cutting of lemon verbena all leaves are taken off, in zonale geraniums from the open ground few if any are left, in coleus and verbena about one half are removed, while in Olea fragrans. Daphne odora, and heath, only enough for planting. Use a sharp knife; but scissors are handy for trimming and sometimes for making cuttings of those small-wooded plants which root easily.
The cuttings of plants with milky juice should be washed before planting. Sometimes the lower ends are allowed to dry for several hours, the tops being protected against wilting. Large and succulent cuttings, e. g., of pineapple, cotyledon and cactus, should be dried before planting by letting them lie on the surface of the propagating-bed for several days, or they may be planted in dry sand at first. Under these conditions a callus forms which tends to prevent decay; but the wood must not shrivel.
Peter Henderson has introduced a method which is likely to increase the percentage of rooted plants, and which is desirable in slow-growing varieties, like the tricolor geraniums. He advises that the cutting should be partly severed and allowed to hang to the parent plant for a few days; this results in a partial callus or even roots, before the cutting is entirely removed.
In planting cuttings, use a dibble or open a V-shaped trench. Never thrust the cutting directly into the soil. Plant deep enough to hold the cutting upright and no deeper (as in Fig. 1171), making due allowance for the sand settling; the distance apart should be just enough to prevent them from pressing against each other. It must be remembered that they stay in the bed only until rooted. As soon as growth begins, they are potted off. When the cuttings are inserted, the sand should be firmly pressed about them, and they should be watered with a syringe or with a fine rose; the forcible application of water compacts the sand, thus excluding air, and prevents undue wilting.
Give shade immediately, using lath shutters outside, cloth screens or papers placed directly on the cuttings within, and attend to this very carefully for the first few days. Lift the shades early in the afternoon, and put them on late in the morning, but keep them on during the middle of the day, thus gradually accustoming them to full light.
Cuttings should never suffer from dryness. The sand should always be kept moist to the verge of wetness. Ventilation should be given on bright days, but all exposure to draft avoided. A good temperature for propagating is from 60° to 65° F.; increasing these figures for tropical plants and reducing them for more hardy kinds. It is debatable whether bottom heat and confined air are advisable for outlines of growing wood. The older gardeners employed both, but now neither is commonly used, except for tropical plants, like croton, or when a constant succession of crops of cuttings is required. There is no doubt that with this aid cuttings will root more quickly, but more skill and care are required, neglect bringing on fungous disease, which results in unhealthy plants or total loss. If bottom heat is used, the average temperature of the bed should be 10° or so above that of the air, but less will suffice. Indeed, in beds made as described above, in good weather the sand is enough warmer than the greenhouse atmosphere to answer every purpose. If a confined air is wanted, ventilation and shading must be carefully looked after, and precautions taken against the accumulation of condensed moisture within the bell-glass or frame.
Although it is tender plants, in the main, that are propagated by cuttings of growing wood, the above methods can be practised advantageously with some hardy plants. The wood, which is invariably more successful if hardened, is obtained either from plants forced for this purpose, e. g., spirea, Deutzia gracilis, or it is gathered in June and July out-of-doors, e.g., lilac, hydrangea. They should be potted off in 2- or 3-inch pots, in a rather sandy soil, when the roots are from ¼ to ½ inch long. It is sometimes good economy to box them, i.e., plant them a few inches apart in flats, when not immediately required.
Some hardy perennials, like Phlox subulata, Campanula carpatica, Gentiana acaulis and the hardy candytuft, can also be easily increased in this way. Make the cuttings 2 to 3 inches long and plant in flats or pots in sand or a sandy soil in October, November or December, before any hard frost. Keep in a coolhouse and pot off when rooted. They make nice plants for planting out the following spring. Plants of this same nature can also be propagated in the open air in autumn. Make the cutting longer, 6 inches when possible, and do the work earlier, in September or in August in some cases.
Cutting of ripened or dormant wood. Figs. 1172-1174.
Many plants grow readily from twigs of the year's growth taken in fall or winter or very early spring. The "soft-wooded" plants usually propagate most readily by this means. These cuttings of mature wood may be either long or short.
Long cuttings of ripened wood in open air.—This method is used to propagate many hardy trees and shrubs, e.g., willows, currants, grapes, forsythia. Wood of the current year's growth is gathered in autumn or early winter, before severe frost, and either stored in a cool cellar, covering with moss or fresh earth to prevent drying, or immediately made into cuttings. These cuttings are usually 6 inches or more long and should contain at least two buds. It is not necessary to cut to a bud at the base, but the upper cut should be just above one. Figs. 1172, 1173. They should be tied in bundles with tarred rope, taking care to have them lie "heads and tails" to facilitate planting, and with the butts on the same level, to promote callusing. They should then be buried in well-drained soil, with the butts down and protected against frost. In early spring they should be firmly planted in V-shaped trenches in well prepared soil: set an inch or so apart, with the rows 1 or 1½ ft. apart. The upper bud should be just at the surface; to prevent suckers the lower buds may be removed. In autumn they should be dug, graded and heeled-in for winter. Some varieties will require a second or third year's growth in the nursery; others are ready for permanent planting, as willows and poplars, which of ten grow 6 feet the first year. This is one of the very cheapest ways of propagating, and will pay when only 25 per cent root. This method is generally used with deciduous-leaved plants, but some conifers, e.g., Siberian arborvitae, will strike. Remove enough twigs to get a clean stem for planting, and allow 2 or 3 inches of top above ground.
The excrescences, knots or knaurs, which are found on the trunks and the main limbs of olive trees, are sometimes used as cuttings for propagation.
Short cuttings of ripened wood. (Fig. 1174.) Cuttings of this class are used under glass with tender or half-hardy species, and sometimes with new introductions, in cases in which the grower is short of stock, and when the plant is delicate and small. The wood should be gathered before severe frost and the cuttings made and planted directly in October and November. Make them from 2 to 4 inches long (sometimes a single eye only is used), and plant with a dibble, in pure sand in pots, pans or flats (boxes about 16 inches square and 3 inches deep). If a layer of potting soil is placed under the sand, the young plants have something to feed on and do not need to be potted so soon after rooting; if this is done, drainage should be given. It is important to keep them cool until a callus is formed or roots produced. If the buds start into growth before this, the cuttings become exhausted and are likely to die. After rooting,—the time required varies from one to six months—they may either be potted or the strong-growing sorts be planted out in well-prepared beds in May or June, where they are likely to make a satisfactory growth. The weaker kinds may remain a year in pots or flats, be wintered in a pit, and planted out the next spring. Some greenhouse plants, e.g., camellia, laurestinus, tender grapes, are propagated in this way with cuttings of fully ripened wood; and others, as cactus and dracena, with wood which is much older. They should be given the care described under the head of "Cuttings of growing wood" (p. 927), but they must not be forced too hard at first. The temperature should be regulated by the nature of the plant. The safest rule to follow is to give a few degrees more heat for propagating than the plant received when the cutting was removed.
Hardy shrubs can also be propagated by cuttings of growing wood, somewhat hardened, planted in coldframes in June and July. They are called "cuttings of green wood, and are made from 4 to 6 inches long and sometimes longer. They are closely planted in sand, or soil one-half sand and one-half leaf- mold, in rows 4 to 6 inches apart. They must be carefully watered, shaded and ventilated for ten days or more after planting. Much of the success of this method depends upon the weather; it brings in a gambling element: a few hot and dry days are dangerous. A light hotbed may be used instead of a coldframe but this means more care. The rooted plants are left in the frame all winter, protected and planted out the following spring.
The cuttings of this class are made of either root or rootstock and are useful in propagating some plants, either in the greenhouse or in the open air. Tender plants, like bouvardia, and those which are hardy but of delicate growth, e.g., Anemone japonica, are handled under glass; blackberries, horse-radish, and so on out-of- doors. The cuttings are made in autumn or winter, the roots of hardy plants being gathered before severe frost and either planted directly or kept in moss until spring. This process of storing develops a callus and has a tendency to produce buds. For greenhouse work, the cuttings are made from 1 to 2 inches long, the larger roots being selected, although the small ones will grow. They are planted in pans or flats, in soil composed of equal parts sand and well-rotted leaf-mold. Ordinarily they are set horizontally. If planted vertically, in cuttings from the true root, the end which was nearest the crown should be uppermost; but if made from the rootstock, that end should be uppermost which grew farthest from the crown. In either case they should be covered, as seeds are covered, and the whole made firm. Root-cuttings of hardy plants should be kept cool at first and brought into heat only when ready to grow. They may be kept in a pit or cool cellar. Tender plants require the same or a little higher temperature than that in which they thrive.
In sweet potato, the tuber is cut lengthwise and laid, with the cut side down, on moist sand or moss, the edges being slightly covered. Buds develop on these edges and are removed when of proper size and treated as cuttings of growing wood, or allowed to remain until rooted. In dracena , (see Fig. 1052, page 842)—and this applies to stem- as well as root -cuttings — the buds are not taken off until rooted the original cutting remains in the sand and sometimes produces a second or even a third crop. The tuberous rootstock of Arum maculatum, and plants of like nature, can be cut into pieces, remembering that the bud-producing portion of arum is the top, and each part will grow successfully. Exercise care in watering and maintain a good temperature.
The rootstocks of cannas are cleaned and cut into pieces 1 ½ to 2 inches long and planted in a warmhouse in February (Fig. 784, p. 657). As soon as buds push and roots from they are potted off and grown until the season for bedding out. Dahlias are not, properly speaking, propagated from rootstock, but by division; the plant cannot produce adventitious buds. There must always be a bit of the crown attached to the tuber. The propagation of dahlias so closely resembles the methods here described that it is perhaps well to mention it.
Root-cuttings for planting in the open ground are made from 4 to 6 inches long, and are planted firmly in V-shaped trenches or furrows in spring, being covered 2 inches or more deep. Roots as large as one's little finger are chosen, and good results are secured with plants of vigorous growth. In plants like lily-of-the- valley, common lilac, calycanthus, Scotch and moss roses, unless short of stock, it is better to encourage the natural growth of the suckers and propagate by division, but they all can be multiplied as above described.
Variegation, curiously enough, is not always reproduced by means of root-cuttings.
Leaf-cuttings. Fig. 1176.
Many leaves are capable of producing roots. Some have the further power of developing buds after rooting, and of these last a few furnish an economical means of bud-propagation, particularly when the stem growth is insufficient. In cotyledon (echeveria) the whole leaf is used, the smaller ones from the flower- stalk being often the best. Choose those that are fully matured, and dry them for a few days on sand, but do not let them shrivel. The treatment, otherwise, is as given above for cuttings of growing wood. In gloxinia and other Gesneraceae, the whole leaf (Fig. 1176), half a leaf, or even a lesser portion, is used. When enough clear petiole is obtainable, no further preparation is needed. When a part only of the leaf is planted, some of the blade must be cut away. As a rule, no bud is developed the first season: a tuber is formed, which will grow in due time.
The common Begonia Rex is increased by leaves in various ways. The whole leaf may be planted as a cutting, keeping the petiole entire or cutting it off where it unites with the blade; or the whole leaf may be pinned or weighted to the surface of moist sand (Figs. 501-503, p. 470), and, if the principal veins are severed at intervals of an inch, a plantlet will appear at every cut. The best way is to divide the leaf into somewhat triangular pieces, each part having a strong vein near the center. Plant in sand, in good temperature, and treat precisely as if they were cuttings of growing wood. Roots and buds will soon grow, and a good plant will result within a reasonable time. Pot off when roots are ¼ inch long. Certain other begonias may be similarly multiplied.
The thickened scales of bulbs, like lilies, can be used for propagation. Remove the scales intact and plant upright, like seeds, in soil made of equal parts of sand and rotted leaf-mold (Fig. 1177). September and October are the usual months for this work. If they are kept in a cool greenhouse, the young bulblets will appear in the course of the winter, but top growth will come later, in summer. This is a slow, laborious process, and is seldom practised except in propagating new varieties. The granular scales of achimenes and plants of like nature can be used for propagating, sowing them in a sandy soil as seeds are sown; but this method is not a good one in ordinary cases. The scales of Zamia horrida have been made to produce new plants, as have also the tunicated scales of an amaryllis.
For further details of cuttage, consult Lindley's "Theory and Practice of Horticulture," 2d ed.: Burbidge, "The Propagation and Improvement of Cultivated Plants;" Peter Henderson's "Practical Floriculture;" Bailey's "Nursery-Book." B. M. Watson. CH
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963