Several of the perennial herbs, such as sage, savory, and thyme, may be easily propagated by means of layers, the stems being pegged down and covered lightly with earth. If the moisture and the temperature be favorable, roots should be formed in three or four weeks and the stem separated from the parent and planted. Often there may be several branches upon the stem, and each of these may be used as a new plantlet provided it has some roots or a rooted part of the main stem attached to it. By this method I have obtained nearly 100 rooted plants from a single specimen of Holt's Mammoth sage grown in a greenhouse. And from the same plant at the same time I have taken more than 100 cuttings. This is not an exceptional feat with this variety, the plants of which are very branchy and often exceed a yard in diameter.
Layering is probably the simplest and most satisfactory method of artificial propagation under ordinary conditions, since the stems are almost sure to take root if undisturbed long enough; and since rooted plants can hardly fail to grow if properly transplanted. Then, too, less apparent time is taken than with plants grown from cuttings and far less than with those grown from seed. In other words, they generally produce a crop sooner than the plants obtained by the other methods set in operation at the same time.
DIVISION
Division of the clumps of such herbs as mint is often practiced, a sharp spade or a lawn edger being used to cut the clump into pieces about 6 inches square. The squares are then placed in new quarters and packed firmly in place with soil. This method is, however, the least satisfactory of all mentioned, because it too frequently deprives the plants of a large amount of roots, thus impairs the growth, and during the first season or two may result in unsymmetrical clumps. If done in early spring before growth starts, least damage is done to the plants.
Holt's Mammoth and Common Sage About Half Natural Size
Artificial methods of propagation, especially those of cuttage and layerage, have the further advantage over propagation by means of seeds, in the perpetuation of desired characters of individual plants, one or more of which may appear in any plantation. These, particularly if more productive than the others, should always be utilized as stock, not merely because their progeny artificially obtained are likely to retain the character and thus probably increase the yield of the plantation, but principally because they may form the nucleus of a choice strain.
Marker for Hotbeds and Cold Frames