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.
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 2 1/2 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.
Fig. 1160. Section of propagating-bed. Shows four pipes beneath, the door in the side, and the frame cover.
Fig. 1161. Permanent propagating-frames in a greenhouse.
Large establishments have one or more houses set apart for this and similar purposes called "propaga-ting-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-glasses 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 5 1/2 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.
Fig. 1162. Cutting-bench shaded with lath.
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 propa-gating-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.