Cultivation.
The genus of resinous plants called Aides, which we have thus described, comprehend many forest trees of great importance ; and it will be, therefore, proper to add a few remarks on their cultivation. Some of them, such as the Larch, the Norway Spruce, the Silver Fir, and the Balm of Gilead, are raised in the nurseries annually in the open ground, in large quantities, for the supply of our plantations; others, such as the Cedar of Lebanon and the Douglas Fir, are procured in much leas abundance, and are treated with more care, being usually kept iu pots until they are finally committed to the earth in the situation they may be subsequently destined to occupy.
All the species are propagated by seeds; they may also be propa gated both by Marching and by cuttings; but it is found that plants 60 obtained are either very ahortlived or stunted, unhealthy, and incapable of becoming vigorous trees. In some of the species, such as the Balm of Gilead and the Silver Fir, the scales of the cones readily separate from their axis, so as to render the extraction of ,the seeds a simple and easy operation; but in others, such as the Larch and the Spruce Fir, the scales will neither separate nor open : in such cases it is necessary, to dry the cones as much as possible, then to split them by means of an Instrument passed up their axis, and afterwards to thresh the portions so separated till the seeds can be sifted out.
Like other resinous seeds, these are perishable unless sown within a few months after the cones have been gathered; they will, however, keep much longer in the cone than if separated ; wherefore, they should always be imported in that state.
It is usual in the nurseries to sow them in the spring in beds of light soil, in which no recent manure has been mixed; they are buried at various depths, according to the force of the vital energy of the species. This has been found by experience, as it is said, to be one inch deep for the Silver Fir; half an inch for the Spruce, Balm of Gilead, and Cedar of Lebanon; a quarter of an inch for the Larch; and less for the American Spruce ; it is, however, probable that these depths are of very little importance. In order to protect the surface of the beds from being dried while the young seeds are sprouting, it is generally overspread with a thin layer of long straw, which is removed as soon as the crop begins generally to appear. During the first season the seedlings remain undisturbed ; the only attention they receive being to keep them from weeds. In the following spring the young plants are taken up carefully, and their roots, being a little shortened, are imbedded in rows about six inches apart, where they remain for one or two years. After this they are transplanted into quarters, in rows a foot or nine inches apart, the planta being about six inches from each other. Having remained in this situation for a year, they are fit to be transferred to the plantation, or they may stand two years in the nursery quarters, and then be taken up and replaced in a situation of the same kind, if circumstances should render such a proceeding desirable. On no account, however, should they be
allowed to remain in the quarters more than two years at a time without being taken out of the ground, because they are apt to form long and strong shoots, which are destroyed in the process of trans plantation, so that the life of many must be either materially injured or wholly sacrificed.
None of the firs should be transplanted at a height exceeding three feet, for the reason last mentioned; and the Larch is the only kind that will remove advantageously even at this size. The Spruce and its allied species may be removed more successfully when from a foot and a half to two feet high. To this there is no other exception than that of plants that have been constantly reared in pots, as the Cedar of Lebanon ; these may be safely removed at any size, if the trans plantation is carefully attended to, because their roots are uninjured in the operation. it should however be remembered, in finally planting out large firs which have been always kept in pots, that it is absolutely necessary that their roots should be spread out among the earth as much a may be practicable without /draining or breaking them ; because, while in pots, they necessarily acquire a spiral direction, which they will not afterwards lose unless it is destroyed at the period of final transplantation; and, if they do not lose it, they are apt to be blown over by high winds, on account of their roots not having pene trated into the earth far enough in a horizontal direction to form the requisite stay to support the trunk and head.
Where great importance is attached to the raising the seeds of rare npecies of fir, it has been found a very beneficial practice to place them between two turfs placed root to root, the one upon the other, and to watch them till the seeds begin to sprout; they are then to be sown in the usual way, when every seed will usually succeed.
No trees are more impatient of pnining than these. They exude, when wounded, so large a quantity of their resinous sap as to become weakened even by a few incisions ; and, if they have suffered many, they are long before they recover from the effects. So great is their symmetry, and so uniformly will their branches form under favourable circumstances, that it will rarely happen that a necessity for the use of the pruning-knife can arise. The great rule to be observed in their management in to allow them ample room for the extension of their branches; if this is attended to, their beauty is not only ensured, but the rate at which they will form their timber will be a full recompense for the space they may occupy.