Any information that can be given in an article short enough to be suitable for amateurs on a subject so extended as this must be confined to a few well known and leading plants most valued for general cultivation. First may be placed the Tuberose, which in most northern states must be artificially forwarded to bloom in perfection in the open air. The seasons are too short for the full development of the flowers in fall unless the bulbs are so forwarded. All that it is necessary to do is to place the dry bulbs in soil in pots or in boxes about May 1st, (not before), keeping them rather dry until they start to grow freely, when more water may be given. Plant the bulbs thus started in the open border, the first week in June. The bulbs while being forwarded may be kept in any place where the thermometer ranges from about 65° to 75° at night. We usually place them under or alongside the hot-water pipes in our greenhouses, covering them up with paper to keep the heat of the pipes from them. Light is not necessary until they have well started to grow. A greenhouse is not essential for starting them in, as a hot-bed, or even a warm sitting room, will do nearly as well. Any one wishing to have their Tuberoses "started" can do it themselves just as well as a florist can, and as the dry bulb costs less than half the price of the started one, and is more safely transported by mail or otherwise, any one taking the trouble to do it will save expense and have the bulbs in better condition for planting.
Some of my readers have seen or cultivated the bulbs known as fancy or spotted-leaved Caladiums. There are probably no plants that assume such varied and wonderful markings of the leaves as these, and when properly grown, they are among the most attractive plants at our horticultural fairs. The continued high temperature necessary for the healthy growth of the Tuberose, is equally indispensable for the Caladium. The bulbs we treat at first exactly in the same manner as the Tuberose; that is, they should not be started much before May 1st, and never should they be kept for any length of time in a less temperature than 65°. They are best started in small pots, and should be shifted into larger ones as soon as these get filled with roots. Started in May, and properly treated, they should be large enough by August or September to require a flower-pot twelve inches in diameter, and the plant should be, according to the variety, from two to three feet in diameter across the leaves. Caladiums require a partial shade, and if kept in a greenhouse during summer, the glass should be shaded, but the light of an ordinary sitting-room would be just about right; so that even those who have not a greenhouse can grow these rather rare and beautiful plants with perfect ease. The only thing necessary if grown as a window plant, is to turn the pot around every few days so that each side may get a proper amount of light - a necessity with all plants grown in windows. The soil best suited for its growth is that known as sandy loam, to which should be added one-third rotted manure or leaf mold.
The same time of starting and a similarly high temperature is required for Begonias of all kinds, Bouvardias, Cissus, Coleuses, Dracaenas, Euphorbias, Poinsettias, and all other plants known as "hot-house" or " tropical," and the same general treatment will in nearly all cases lead to satisfactory results. All of the plants or bulbs referred to will dwindle or die if long kept in a low temperature, and hence it is important that amateurs should remember that they ought not to attempt the cultivation of these plants unless they have the means of steadily keeping up the necessary high temperature. For that reason we recommend that they should not be started before May, as then they run less risk of being chilled.
What is true of tropical bulbs or plants is equally so of tropical seeds. Those who have not had experience or who have not the means of keeping up the necessary high temperature, should not sow the seeds of tropical plants before April 1st. Of vegetable seeds, the best known of this class are the Tomato, Pepper, and Egg-plant. I know they are often started in March in hot-beds or greenhouses with satisfactory results, but let any one try the experiment of sowing on March 1st and on April 1st, and note the result in the earliness of the crops, from the two sowings, and he will find that the chances are that the last shall be first; if it were always practicable to keep the necessary temperature steadily along, the first sown would be the first, but this is often very difficult to accomplish, while there is but little difficulty with the later sowing, as assistance is then given by the increasing outside temperature. For this reason seeds of tropical annual flowers, such as Amaranths of all kinds, Balsams, Salvias, Double Portulacas, Cannas, Coxcombs, Zinnias, etc., should not be sown before April in the hot-bed, or if in the open ground, in this latitude, not before May 15th.