This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
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 1 1/2 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 often 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 arbor-vitae, 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.
(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.
Fig. 1173. Cuttings of grape, to show how planted.
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.