PROPAGATION
SEEDS
Most herbs may be readily propagated by means of seeds. Some, however, such as tarragon, which does not produce seed, and several other perennial kinds, are propagated by division, layers, or cuttings. In general, propagation by means of seed is considered most satisfactory. Since the seeds in many instances are small or are slow to germinate, they are usually sown in shallow boxes or seed pans. When the seedlings are large enough to be handled they are transplanted to small pots or somewhat deeper flats or boxes, a couple of inches being allowed between the plants. When conditions are favorable in the garden; that is, when the soil is moist and warm and the season has become settled, the plantlets may be removed to permanent quarters.
If the seed be sown out of doors, it is a good practice to sow a few radish seeds in the same row with the herb seeds, particularly if these latter take a long time to germinate or are very small, as marjoram, savory and thyme. The variety of radish chosen should be a turnip-rooted sort of exceedingly rapid growth, and with few and small leaves. The radishes serve to mark the rows and thus enable cultivation to commence much earlier than if the herbs were sown alone. They should be pulled early–the earlier the better after the herb plantlets appear. Never should the radishes be allowed to crowd the herbs.
By the narration of a little incident, I may illustrate the necessity of sowing these radish seeds thinly. Having explained to some juvenile gardeners that the radish seeds should be dropped so far apart among the other seeds that they would look lonesome in the bottoms of the rows–not more than six seeds to the foot–and having illustrated my meaning by sowing a row myself, I let each one take his turn at sowing. While I watched them all went well. But, alas, for precept and example! To judge by the general result after the plants were up, the seedsman might justifiably have guaranteed the seed to germinate about 500 per cent, because each boy declared that _he_ sowed _his_ rows thinly. Nevertheless, there was a stand of radishes that would have gladdened the heart of a lawn maker! The rows looked like regiments drawn up in close order and not, as was desired, merely lines of scattered skirmishers. In many places there were more than 100 to the foot! Fortunately the variety was a quick-maturing kind and the crop, for such it became, was harvested before any damage was done the slow-appearing seedlings, whose positions the radishes were intended to indicate.
CUTTINGS
No herbs are so easy to propagate by means of cuttings as spearmint, peppermint, and their relatives which have underground stems. Every joint of these stems will produce a new plant if placed in somewhat moist soil. Often, however, this ability is a disadvantage, because the plants are prone to spread and become a nuisance unless watched. Hence such plants should be placed where they will not have their roots cut by tools used close to them. When they seem to be extending, their borders should be trimmed with a sharp spade pushed vertically full depth into the soil and all the earth beyond the clump thus restricted should be shaken out with a garden fork and the cut pieces of mint removed. Further, the forked-over ground should be hoed every week during the remainder of the season, to destroy lurking plantlets.
The other perennial and biennial herbs may be readily propagated by means of stem cuttings or “slips,” which are generally as easy to manage as verbenas, geraniums and other “house plants.” The cuttings may be made of either fully ripened wood of the preceding or the current season, or they may be of firm, not succulent green stems. After trimming off all but a few of the upper leaves, which should be clipped to reduce transpiration, the cuttings–never more than 4 or 5 inches long–should be plunged nearly full depth in well-shaded, rather light, porous, well-drained loam where they should remain undisturbed until they show evidences of growth. Then they may be transplanted. While in the cutting bed they must never be allowed to become dry. This is especially true of greenwood cuttings made during the summer. These should always have the coolest, shadiest corner in the garden. The cuttings taken in the spring should be set in the garden as soon as rooted; but the summer cuttings, especially if taken late, should generally be left in their beds until the following spring. They may, however, be removed for winter use to window boxes or the greenhouse benches.
Often the plants grown in window boxes may supply the early cuttings, which may be rooted in the house. Where a greenhouse is available, a few plants may be transplanted in autumn either from the garden or from the bed of summer cuttings just mentioned, kept in a rather cool temperature during the winter and drawn upon for cuttings as the stems become sufficiently mature. The rooting may take place in a regular cutting bench, or it may occur in the soil out of doors, the plantlets being transplanted to pots as soon as they have rooted well.
If a large number of plants is desired, a hotbed may be called into requisition in early spring and the plants hardened off in cold frames as the season advances. Hardening off is essential with all plants grown under glass for outdoor planting, because unless the plants be inured to outside temperatures before being placed in the open ground, they will probably suffer a check, if they do not succumb wholly to the unaccustomed conditions. If well managed they should be injured not at all.
LAYERS
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.
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.
Except in the respects mentioned, these methods of propagation are not notably superior to propagation by means of good seed, which, by the way, is not overabundant. By the consumption of a little extra time, any desired number of plants may be obtained from seed. At any rate, seed is what one must start with in nearly every case.
TRANSPLANTING
No more care is required in transplanting herbs than in resetting other plants, but unless a few essentials are realized in practice the results are sure to be unsatisfactory. Of course, the ideal way is to grow the plants in small flower pots and when they have formed a ball of roots, to set them in the garden. The next best is to grow them in seed pans or flats (shallow boxes) in which they should be set several inches apart as soon as large enough to handle, and in which they should be allowed to grow for a few weeks, to form a mass of roots. When these plants are to be set in the garden they should be broken apart by hand with as little loss of roots as possible.
But where neither of these plans can be practiced, as in the growing of the plants in little nursery beds, either in hotbeds, cold frames or in the garden border, the plants should be “pricked out,” that is, transplanted while very small to a second nursery bed, in order to make them “stocky” or sturdy and better able to take care of themselves when removed to final quarters. If this be done there should be no need of clipping back the tops to balance an excessive loss of roots, a necessity in case the plants are not so treated, or in case they become large or lanky in the second bed.
In all cases it is best to transplant when the ground is moist, as it is immediately after being dug or plowed. But this cannot always be arranged, neither can one always count upon a shower to moisten the soil just after the plants have been set. If advantage can be taken of an approaching rainfall, it should be done, because this is the ideal time for transplanting. It is much better than immediately after, which is perhaps next best. Transplanting in cloudy weather and toward evening is better than in sunny weather and in the morning.
Since the weather is prone to be coy, if not fickle, the manual part of transplanting should always be properly done. The plants should always be taken up with as little loss of roots as possible, be kept exposed to the air as short a time as possible, and when set in the ground have the soil packed firmly about their roots, so firmly that the operator may think it is almost too firm. After setting, the surface soil should be made loose, so as to act as a mulch and prevent the loss of moisture from the packed lower layer. If the ground be dry a hole may be made beside the plant and filled with water–LOTS OF WATER–and when it has soaked away and the soil seems to be drying, the surface should be made smooth and loose as already mentioned. If possible such times should be avoided, because of the extra work entailed and the probable increased loss due to the unfavorable conditions.
