They are of three kinds, - viz., hardy, or such as grow m the open border; half-hardy, such as will not stand out over winter, or requiring a frame or the green-house; and stove, or those that will not grow to perfection without artificial heat. Of these last we shall have nothing to say. Many of the half-hardy are perfected when planted in the open ground in the spring, and are sometimes called spring bulbs, as the Gladiolus, etc.
Hardy bulbs, with few exceptions, are remarkably easy of sultivation, and, if planted in proper soil and situation, seldom fail to produce plenty of offsets and seeds for propagation.
The best kind of soil for their growth is a light loam, rather sandy than otherwise, yet not too light, or the bulbs will be injured during the heat of summer, and, if adhesive, they invariably grow weakly, and seldom flower.
As to the depth the different bulbs require to be planted in the ground, no certain rule can be laid down, as some species require to be planted from three to five inches, while others not more than one and a half, deep. The different depths will be given as each variety in species is described.
Encourage as much as possible the growth of the leaves, by giving them free exposure to light and air; for on the full development of these depends the success of the bulbs flowering another year. If the leaves grow strong, a good quantity of strong pulp is stored up in the bulbs, and a good bloom is the consequence.
Never, if it can be avoided, disturb the roots by removal during their growth: but if obliged to do so, select a wet day, and take them up with good balls, so as not to injure the fibrous roots.
The only time to remove them with success, is during the time of their torpidity, at which time the offsets may be separated, and planted where the cultivator may judge best.
The season of rest, for most bulbs, happens shortly after they have done flowering. Tulip and Hyacinth bulbs are generally ripe in about one month from the time of flowering. As soon as the foliage of the Tulip turns purple and begins to dry, the bulbs may be taken up; and the Hyacinth, before the foliage is fully decayed. As a general rule, when the tops have quite died down, the bulbs may be taken up and separated.
With the exception of Tulips, Hyacinths, Narcissus, and some others, most hardy bulbs are injured if kept long out of ground, as the Lily tribe, Crown Imperial, etc. It is best to plant immediately offsets of bulbs, of every description, for if kept long out of ground they become exhausted and perish. Bulbs that have commenced growing, before planting, are always weakened; yet ignorant purchasers will frequently select such because they look more lively. If they have made much growth, the bulb will not flower at all.
Some tuberous roots are classed with bulbous roots. Strictly speaking, it is not correct, but for convenience sake we shall so consider them. The Dahlia and Peony are, properly, tuberous roots. Of these, directions for cultivation will be given when described.