The growing season never arrives early enough for the enthusiastic boy gardener, so he provides himself with a hotbed, by which means it is possible to have radishes, lettuce, and other early vegetables a month before they can be raised outdoors. Now, a hotbed is such a simple piece of garden equipment to make, and so easily operated, that there is no reason why every boy who goes in for gardening should not have one.
Excerpt from the book: “Carpentry & mechanics for boys: up-to-the-minute handicraft” by Hall, A. Neely (Albert Neely), Publication date 1918 / Publisher Boston: Lothrop, Lee & Shepard Co.
A hotbed is in reality a small greenhouse, heated by fermenting manure. It consists of a pit from 2 to 3 feet deep, filled with manure to within 6 inches of the ground level, with a 6-inch top dressing of garden soil. The front wall of the frame extends 6 inches above ground, the rear wall 12 inches, the sides slope from the height of the front wall to the height of the rear wall, and the open top is protected by glazed sash.
The Size to Make the Hotbed will be determined by the size and number of sash at hand. Storm-sash or old window sash will do. Regular hotbed sash can be purchased at a door-and-sash mill, and from dealers handling garden accessories, in size 3 feet wide and 6 feet long.
A Single-Sash Hotbed is shown in Fig. 582. If a larger bed is wanted, the frame can be made two or three times as wide, and two or three sash used. Figure 581 shows a four-sash hotbed.
Figure 583 shows a longitudinal section of the hotbed frame and pit. Corner posts A of the framework (Fig. 584) are 2-by-4s, side boards B and end boards E and F (Fig. 584) are cut from I-by-8s, and boards C and G are I-by 6s. Rip a triangular strip from the upper edge of boards B, as shown in Fig. 585, so one end will measure 1% inches wide, the other end 7% inches wide.
The framework must be made enough narrower than the sash so the sash will lap over the sides, and 2 or 3 inches longer than the sash to allow for the strip H (Fig. 583), which is nailed across the top as a hinge-strip to screw the sash hinges to. Side pieces B will be of the right length for sash 6 feet long, if cut as shown in Fig. 585.
To Assemble the Framework nail side boards B and C to corner posts A, then connect the two frames thus formed with boards E, F, and G. Batten the side boards at their centers with pieces D.
Dig the Hotbed Pit of the right depth so the lower edge of framework boards C, E, and G will come 2 inches below the ground surface.
Filling the Pit.
Procure enough horse manure to fill the pit to a depth of 2 feet (Fig. 583). Pile it up in a heap beside the hotbed, sprinkle it with water, and allow it to remain exposed to the air for two or three days, so the fermenting process will get well under way. Then throw the manure into the hotbed pit, and close down the sash. The action of the sun’s rays passing through the glass will increase the fermenting, and the temperature within the hotbed will be raised considerably above 100 degrees. Before the top soil is spread over the manure, the temperature must be reduced to about 90 degrees, which temperature must be taken with a thermometer. To reduce the temperature, raise the sash. Make the top dressing 6 inches in depth. Use the best garden soil that you can get.
If your soil is heavy, add a little sand to it. Bank up earth around the outside of the hotbed frame for insulation.
The temperature of the soil must not be too great, else the plant roots will burn out. This must be regulated carefully by raising the sash when necessary, to allow excess
heat to escape. Raising the sash will also provide the plants with necessary fresh air, but you must use judgment in opening the sash, lest you freeze your plants. Keep the sash closed at night during severe weather, and cover it with pieces of carpet or with straw mats, for additional protection.
Water the hotbed regularly, after the seeds have sprouted, doing this about mid-day so the leaves will dry off before sundown.
A Cold-Frame differs from a hotbed only by the omission of the manure heating-agent. Sunlight alone is depended upon for heat. Consequently, the cold-frame can be depended upon only for forcing plants after the severe weather has passed. You can use the hotbed as a cold-frame after the manure has cooled.