One to two joints is the proper length of a greenwood cutting. If of two joints, the lower leaves should be cut off and the upper leaves cut in two so that they do not present their entire surface to the air and thereby evaporate the plant juices too rapidly. If the cutting is of only one joint, the lower end is usually cut just above a joint. In either case, the cuttings are usually inserted in sand or well-washed gravel, nearly or quite up to the leaves. Keep the bed uniformly moist throughout its depth, but avoid any soil which holds so much moisture that it becomes muddy and sour. These cuttings should be shaded until they begin to emit their roots. Coleus, geraniums, fuchsias, carnations, and nearly all the common greenhouse and house plants, are propagated by these cuttings or slips (Figs. 123, 124).
Leaf-cuttings are often used for the fancy-leaved begonias, gloxinias, and a few other plants. The young plant usually arises most readily from the leaf-stalk or petiole. The leaf, therefore, is inserted into the ground much as a green cutting is. Begonia leaves will throw out young plants from the main ribs when these veins or ribs are cut. Therefore, well-grown and firm begonia leaves are sometimes laid flat on the sand and the main veins cut; then the leaf is weighted down with pebbles or pegs so that these cut surfaces come into intimate contact with the soil beneath. The usual way, however, is to cut a triangular piece of the leaf (Fig. 125) and insert the tip in sand. So long as the cutting is alive, do not be discouraged, even if it do not start.
VIII. A well-planted entrance. Common trees and bushes, with Boston ivy on the post, and Berberis Thunbergii in front.
General treatment of cuttings.
In the growing of all greenwood and leaf-cuttings, it is well to remember that they should have a gentle bottom heat; the soil should be such that it will hold moisture and yet not remain wet; the air about the tops should not become close and stagnant, else the plants will damp off; and the tops should be shaded for a time. In order to control all the conditions, such cuttings are grown under cover, as in a greenhouse, coldframe, or a box in the residence window.
An excellent method of starting cuttings in the living room is to make a double pot, as shown in Fig. 126. Inside a 6-in. pot set a 4-in. pot. Fill the bottom, a, with gravel or bits of brick, for drainage. Plug the hole in the inside pot. Fill the spaces between, c, with earth, and in this set the cuttings. Water may be poured into the inner pot, b, to supply the moisture.