Greenhouse, like those taken outdoors,, are of three main classes, soft, half-ripe, and hard wooded. The first are prepared from young shoots of herbaceous plants or shrubs, the second and third from half-grown and fully grown shoots respectively of shrubs and half-shrubby plants only. Young must be rooted quickly. For this reason they are usually best in a propagating frame, and shaded until rooted. Cuttings are prepared in the same way as those of outdoor plants,. Bottom heat, i.e. heat coming from below through the soil (as in a propagating box), is of particular service in helping soft cuttings to quickly. Root-forming may be used with the same object. Various automatic misting devices are also available and, if used, cuttings need not be shut up in a frame or .
Composts for cuttings are usually very sandy and no fertilizers should be included.
Leaf Cuttings. Theof certain plants, e.g. gloxinias, rex, streptocarpus, and achimenes, will . Well-developed are pegged or weighted to the surface of sandy soil in a propagating frame, and are kept moist and shaded. Sometimes incisions are made across the main veins. Plantlets are formed at these incisions and at the base. Plantlets also form along the fronds of some ferns, e.g. Polysiichum angulare and Asplenium bulbiferum, if these are pegged firmly to the soil round the parent plant without being detached.