Seedlings can be most easily started and grown, at least up to the time of pricking out, in light, well-ventilated greenhouses, and many large growers have them for this specific purpose. Houses for starting tomato plants should be so situated as to be fully exposed to the sun and not shaded in any way; be provided with heating apparatus by which a night temperature of 60 and up to one of 80° F. in the day can be maintained even in the coldest weather and darkest days likely to occur for 60 to 90 days before the plants can be safely set out in the open field; and the houses should be well glazed and ventilated.
Houses well suited for this purpose are often built of hotbed sash with no frame but a simple ridge-board and sides 1 or 2 feet high, head room being gained by a central sunken path and the sash so fastened in place that they may be easily lifted to give ventilation or entirely removed to give full exposure to sunshine, or for storing when the house is not needed. Hotbed sash 3x6 feet with side-bars projecting at the ends to facilitate fastening them in place are usually kept by dealers, who offer them at from $1.50 to $3 each, according to the quality of the material used.
A hot water heating apparatus is the best, but often one can use a brick furnace or an iron heating stove, connected with a flue of sewer or drain-pipe that will answer very well and cost much less. It requires but 6 to 10 square feet of bench to start plants enough for an acre, and a house costing only from $25 to $50 will enable one to grow plants enough for 20 acres up to the stage when they can be pricked out into sash or cloth-covered cold-frames in which they can be grown on to the size best suited for setting in the field. When a grower plants less than 5 acres it is often better for him to sow his seed in flats or shallow boxes and arrange to have these cared for in some neighboring greenhouse for the 10 to 20 days before they can be pricked out.
CHAPTER IX
Hotbeds and Cold-frames
Plants can be advantageously started and even grown on to the size for setting in open ground in hotbeds. In building these of manure it is important to select a spot where there is no danger of standing water, even after the heaviest rains, and it is well to remove the soil to a depth of 6 inches or 1 foot from a space about 2 feet larger each way than the bed and to build the manure up squarely to a hight of 2 to 3 feet. It is also very important that the bed of manure be of uniform composition as regards mixture of straw and also as to age, density and moisture, so as to secure uniformity in heating. This can be accomplished by shaking out and evenly spreading each forkful and repeatedly and evenly tramping down as the bed is built up. Unless this work is well and carefully done the bed will heat and settle unevenly, making it impossible to secure uniformity of growth in different parts.
Hotbed frames should be of a size to carry four to six 3x6-foot sash, and made of lumber so fastened together that they can be easily knocked apart and stored when not in use. They should be about 10 inches high in front and 16 or 18 inches at the back, care being taken that if the back is made of two boards one of them be narrow and at the bottom so that the crack between them can be covered by banking up with manure or earth. In placing them on the manure short pieces of board should be laid under the corners to prevent their settling in the manure unevenly. I prefer to sow the seed in flats or shallow boxes filled with rich but sandy and very friable soil, and set these on a layer of sifted coal ashes covering the manure and made perfectly level, but many growers sow on soil resting directly on the manure; if this is done the soil should be light and friable and made perfectly level. A perspective view of a three-sash hotbed is given in Fig. 13, and of a cross-section in Fig. 14.
