Raising trees from seed requires more care and attention than persons unacquainted with their growth are inclined to consider. The leading thought of inexperience is that nature supplies every want for the nourishment and thrift of plants; and that all that is necessary for theirproduction is to procure and sow the seed, and the earth will of itself, without further trouble, bring forth its increase. Practice and experience point to a further necessity, and convince us that this is not so; but that in the preparation of the soil, sowing of seed, after-culture, and protective measures against the influence of climate the tree-grower will find sufficient for his participation to keep him from idleness and inconsiderate conclusions.
The time for sowing the seed of the different species of trees varies so considerably that no decided information on this subject can be given for the collective genera. Seeds of different species, or even varieties of the same species, differ in vitality so widely that, to determine the time of the seasonable sowing of each separately, experience alone will teach; yet the vitality in seed of some species may be prolonged by due regard to the conditions of treatment, while that in others will seldom exist after the first season. Therefore, to accommodate the vital spark in seed of all species, the most favorable time of sowing is immediately after the gathering in, precaution being, of course, taken in the meantime for their preservation against influences of climate. The ground to be sown should be ploughed deep and thoroughly pulverized by a number of harrowings and rakings previous to sowing the seed, and, if not naturally rich, should be made so by an addition of some of the many manures in general use, such as old barn-yard, leaf-mould, rotted sods, bone-dust, or ashes. The seed soil being thus far prepared, shallow trenches of about one foot wide and at two to four feet intervals, according to the intended manner of cultivating, are to be run, and in these the seeds should be strewn at about two inches distance between each (to allow for the thrift of the young sprouts), and covered over evenly with soil to the depth of from one to two inches. All that is now required for the production of healthy growth is to keep the weeds under, and the soil loose between the trenches with cultivator or spading-fork, and prevent the appearance of obnoxious growths among the young plants.
Some varieties of plants require shading from the sun and protection from the first winter's frost, and for this reason are sown in beds about four feet square, so as conveniently to allow the construction of a frame to ward off any injurious influences which might naturally be brought to bear against the thrift of the young seedlings. The soil in these frames should be composted to the same degree of fineness and richness as that required in trench-seeding in the open ground; but this will depend entirely upon the variety which it is intended to nourish. No general rule can be applied, either for protection or richness of soil, as each separate species of tree has its own peculiarities in these respects, and thrives only when afforded a sufficiency of soil and climate according to its natural habit.
The seed may be sown broadcast in these beds, and covered lightly with fine leaf-mould, after which the frame may be constructed about them, consisting of boards a foot or more in width, placed round the edges of the bed and covered by a lath screen or coarse matting. The lath screen is considered the most convenient covering, as it admits the genial warmth of the sun to the plants without exposing them to its full influence.