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.
