(34) NURSERY PROPAGATION AND CULTURE OF TREES
A nursery is a plot of ground devoted to the propagation and rearing trees; it should as far as possible be exempt from the influence of frost, which prevails in low situations, and it ought to contain a variety of soils. As a general principle, all seeds will germinate in any soil provided it contains vegetable matter, and is friable, free of stones, and well drained, with a convenient supply of water. If a nursery therefore contains the three leading soils, sand, loam. And peat, it will suffice for all required purposes. With regard to climate, all deficiencies which occur in Britain may be met by glazed frames for raising the more tender kinds. It is the interest of the nurseryman to have his nursery in a fine climate, and in deep fertile soil, that he may raise large vigorous plants in the shortest period; but it is the interest of the purchaser to have the plants reared in a climate and soil inferior to that into which they are to be transplanted, because, when this is done, instead of the plants receiving a check, as is usually the case, they will be improved by transplanting. The strength of a plant and its suitableness for successful transplanting consists in all its parts being developed, in the thorough ripening of its wool, and in the dormant state of its fibrous roots. If by any mode of culture these requisites can be obtained, together with the long and thick shoots which are produced by growing the plants in deep rich soil, so much the better; but in the climate of Britain trees reared in nurseries with inferior and unmanured soil are likely to prove most hardy. Those who plant in mountainous districts will always find it better to have their nurseries on the sides of mountains than in the valleys.
Propagation. - Trees are chiefly propagated by seeds, but also by cuttings, layers, budding, and grafting. The timber-trees of all countries are raised from seeds, with a few exception, such as the poplar and willow, which are raised from cuttings, and some species of elm, lime, and a few others, which are raised from layers or by grafting. Most ornamental trees are raised by some of these artificial methods, because in this country they seldom ripen seeds. Thus, all the American oaks may be grafted on the common British oak. Most of the foreign maples and birches are raised by layers, most of the ornamental thorns by budding and grafting, and willows and poplars by cuttings. All plants which do not ripen seeds readily are propagated artificially, and that mode is preferred by the nurseryman, which experience has proved will produce the largest and most vigorous plants in the shortest time. Thus, though more suitable plants would be produced by raising the plane and poplar from cuttings, because in that case nature would adjust the tops to the power of the roots, yet as much larger plants are produced by layers, that mode is preferred in commercial nurseries. The lime tree and English elm ripen their seeds in Britain, but large plants are much more rapidly procured in the first case by layers, and in the second by grafting: the mode by the which the largest plants are most rapidly are most rapidly produced need not always give way to the slower method; but in most cases, it would be advantageous to the purchaser that the slower mode should be adopted. According to some writers, seedling plants are of greater durability than those raised in any other way; but though this may be true in some cases it is not universally applicable, as we know that a bud produces as perfect a plant as a seed; the only difference being that the bud seems more fully imbued with the peculiarities of the individual which produced it than the seed. The poplar, willow, vine, &c., have been propagated by cuttings from time immemorial, and appear to possess respectively the same properties now that they did in the days of the Romans. Seeds should be collected when mature from the best specimens; and should either be sown immediately, or preserved in a place where they will undergo few atmospheric changes till the proper sowing season, which in most cases will be the following spring. Nature, it may be observed, sows all her seeds soon after they are matured; that is, they drop from the tree upon the ground in autumn or the beginning of winter, or, in the case of some trees, such as the conifers, not till spring; but when seeds are thus left to sow themselves many are destroyed by animals, many fall in unfavourable positions for germination, and only a small proportion produce plants. It is for the arboriculturist to study nature's more of sowing, and to imitate only her favourable features. The greater number of seeds may be stored till the following spring, that is, till February or March, and then be committed to the soil. Poplar and willow seeds, however, ripen early, and when sown immediately on dropping from the tree, often come up in the course of a few weeks; whereas, if they are kept till spring, the greater number do not come up at all; and seeds which lie two years in the ground before coming up, such as those of the hawthorn, the holly, &c., may be kept till the second spring before they are sown.
In order to show the treatment required for different kinds of seeds, and the plants raised from them, it will be convenient to throw them into the following groups: - Trees producing (1) cones; (2) nuts, acorns, masts, or keys; (3) cottony or feathery seeds; (4) fleshy fruits; or (5) leguminous seeds.
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