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Propagation (Any method by which plants can)

Any method by which plants can be increased in quantity, however slow the process may be, is rightly referred to as being applicable for the purpose of Propagation. Plants are propagated in various ways some which increase at a most rapid rate by one method cannot be similarly raised by another; occasionally, they cannot be raised at all. The principal modes are those of seeds, cuttings, layers, offsets, bulbs, tubers, suckers, runners, and division of the plant or rootstock. Budding and grafting afford facilities for the rapid Propagation of such plants as under certain conditions may be successfully dealt with; and sometimes leaves are inserted, with the result that new plants or bulbs will eventually form on the firm parts of the main midribs where incisions have been made. Under Budding, Cuttings, Grafting, Layering, and Leaf Propagation, details may be found of the ways in which these several systems of Propagation are adopted in practice, which it is unnecessary to repeat under this heading.

Propagation by seeds is the most natural mode, and is, consequently, the one by which the vast majority of plants naturally spread and reproduce their species more or less true, according as the flowers are subjected or disposed to become influenced by foreign pollen affecting their fertilisation. If all plants were naturally to reproduce themselves true from seeds, the endless variety represented, for instance, in florists' flowers, could not possibly have been obtained by artificial fertilising and cross-breeding, neither could further improvements be so rapidly made. Where exact counterparts of plants cannot be insured by seed-saving, there is generally some one or more of the other methods of Propagation which can be successfully applied, as the insertion of cuttings, buds, or grafts, which generally retain their distinctive characters, although often--as in budding and grafting--supported by sap which is not that of a plant or tree of the same species, nor, maybe, even of the same genus. The great number of annuals in cultivation must of necessity be propagated from seeds, as their roots do not live long after the seed comes to maturity. The conditions requisite for successful Propagation by seeds, are the proper ripening beforehand of the latter, their right preservation during the interval between collecting and sowing, so as to insure the retention of all germinative properties, and their insertion in soil at the proper time, under conditions favourable to rapid or slow development into plants, as individual sorts may be naturally disposed. Some seeds, even when perfectly matured, retain their germinative properties but a comparatively short time; while others, kept under favourable conditions, are just as good at the end of four, or frequently more, years, as in the first after being gathered. When old seeds of flower or kitchen garden crops are intended for sowing, a few of each should be tested beforehand, in order to ascertain the proportion of good ones in a given quantity. This may easily be done, by sowing a potful, and placing them in a little heat. A seed-room kept at about 45deg., and not much affected by outside fluctuations of temperature, is best suited for the general preservation of seeds, from the time of collecting them until the period for sowing; it should have a boarded floor, and be kept quite dry. There are, however, many seeds, especially those of trees, which lose their vitality if kept dry; these should be placed in sand, soil, damp moss, or some other substance suitable for preserving them, until the proper time for sowing arrives. This varies considerably with different plants, and as those raised from seed are extremely numerous, it is impossible to refer to them in more than limited and very general terms. One of the chief considerations is that of sowing so that the young plants shall appear above ground at a season suitable to their after-development. Tender annuals, that will not withstand cold weather, must be sown in spring; hardy ones sometimes succeed and flower all the better if they are established by that season. Seeds of plants that are biennial--that is, do not flower until the second year--require sowing before, or soon after, midsummer, a season favourable to germination, and one which allows the plants, when obtained, to become established before the winter. There are numerous plants grown from seed for indoor decoration, the season for sowing which depends very much on the time when the product is required. Gardening supplies are in constant demand, and sowing for succession is one of the gardener's chief considerations, as it affects so seriously his system adopted for providing what is requisite at the proper time. There are various methods of seed-sowing, but in the open ground they may practically be reduced to two, namely, scattering indiscriminately or broadcast, and sowing in drills. The last-named is the one now most generally practised, as it affords more convenient opportunities for cleaning and thinning the crops or seedlings, as the case may be, than the broadcast system does. Under glass, shallow pans are perhaps most suitable; they afford a larger top surface than pots, and this is often desirable for enabling one to sow thinly. Whether pans or pots are used, they should always be thoroughly clean and dry, and be well drained. Seeds of and description may be said to require a lighter soil wherein to germinate than that in which the plants will grow when established. Even those of forest-trees, which fall and root themselves into the earth, are naturally provided with a covering of leaf-soil formed by the decay of the leaves which the trees themselves shed. Encouragement to free root action is first essential, and this is usually best given by the use of a light compost, into which the roots can readily enter; any special requirements can be provided when they are stronger, and when nutriment is necessary to assist in building up the plant's tissues. A rule which is sometimes adopted, and which is not altogether to be considered inapplicable at any time, is that of covering seeds, when sowing, with an amount of soil about equal to their own depth. If the seeds were very small, and covered deep with soil, in all probability, the plants would perish before reaching the surface; large seeds, which are generally of a much stronger constitution, are more likely to succeed. It is, however, noticeable that some large trees have comparatively minute seeds, which require very careful treatment when young specimens are being raised.

Passing on to refer briefly to the other methods of Propagation enumerated, cuttings are perhaps the most useful. Nearly all soft-wooded plants are readily increased by them, and a very large proportion of hard-wooded ones that are not entirely limited to being increased from seeds. Cuttings require to be of different degrees of firmness. A proper knowledge of various plants must be acquired from experience before successful propagating can be practised. Some cuttings emit roots from almost any part of the stem, while others need a joint or heel, and preparation of an exact nature, to insure the emission of roots. Offsets, tubers, bulbs, and corms, are formed, in some cases, on the stems of plants which bear them, but more generally about their roots. Where they are produced, an easy mode of Propagation is effected by separating or lifting them when the old plants ripen and their tops decay. Tubers admit of being cut into several pieces, each of which will eventually form another plant if it is provided with a perfect eye or bud that can be preserved from injury after being planted; the Potato is a well-known example of this. Corms of the Crocus will also be familiar; they are formed in quantity round the old one, and should be taken up and replanted separately each year. Propagation from suckers is a simple proceeding; it consists in taking up the sucker, with all its roots, and replanting it at any time when the parent plant or tree may also be safely removed. Suckers are not always to be favoured; they are inclined to similarly reproduce themselves, and rob sap which should proceed to the one main stem. Such things as Filberts, Lilacs, Raspberries, &c., may, however, be propagated from suckers; and for an example of plants in pots which may be similarly increased, Chrysanthemums may be cited. Runners proceed along the ground, and form small plants, which are first nourished by the parent, but afterwards root and support themselves. Varieties of Strawberries are almost exclusively propagated by runners, and there are several other examples. Propagation by division is generally understood to mean the parting of the rootstock of a plant and inserting the pieces thus obtained with roots, to form separate plants. It is a very important method, often available when many of the others are impracticable, or employed with difficulty or uncertainty.