Construction and operation of hotbeds on a garden plot

Installing hotbeds allows starting the season 50–60 days earlier than usual. This makes it possible to grow high-quality transplants of nightshade crops (tomatoes, peppers, eggplants) and obtain early greens and cucumbers. Heating such a structure does not require electricity — heat is released during the decomposition of organic matter. Any wooden waste and glass are suitable for assembly.

Site selection and pit preparation

A hotbed is placed in a well-lit, wind-protected area with an east-to-west orientation. Additionally, a windbreak made of brushwood or boards can be installed on the north side, ensuring that its shadow does not fall on the frames. The structure is made collapsible using bolts or screws, and all joints are marked before winter storage for quick assembly in spring. The frame is covered with glass frames or durable polyethylene film.

• Film thickness — up to 0.3 mm
• Hotbed frame size — 106x160 cm
• Linseed oil consumption per frame — 0.4 kg
• Top width of the pit — 1.6 m
• Bottom width of the pit — 1.2 m

The depth of the pit depends on the planned planting dates and the type of structure heating. Frames are built from boards, timber, old logs, or laid out from leftover bricks. The south side edge is made lower and the north side higher to ensure the required angle of the frames.

For convenience in plant care, boards are laid inside the frame on support beams, which allows for pricking out transplants while semi-reclining. The soil is piled at an angle towards the south or formed in steps. A stepped soil profile with a hotbed width of 1.5 m increases the usable area by more than 0.3 m across its entire width.

Design options and assembly technology

A sunken solar hotbed is set in a pit up to 50 cm deep. An insulating material is laid on the bottom: sand, slag, gravel, dry leaves, or roofing felt. If biofuel is available, it is spread in a layer of 20–30 cm and covered with a layer of soil 12–18 cm thick. Such a hotbed is suitable for forcing radishes, dill, green onions, and hardening indoor transplants in pots.

An above-ground hotbed is mounted on a previously ploughed bed, using a frame 160 cm wide and 20–30 cm high. On the outside, the structure is mounded with soil and covered with light frames. A frame made of eight beams (board thickness 30–35 mm) can be easily lifted by one worker. The sides of the beams are carefully leveled to avoid gaps when joining the frames.

1. Cut grooves at the ends of the side beams and insert the tenoned ends of the end beams into them.
2. Prepare four holes on the inner side of the end beam and insert the middle beams into them.
3. Fasten all joints with nails at 4–5 cm intervals.
4. Secure a strip to the end beams for rigidity.

Near the south wall of an outbuilding, a lean-to hotbed can be quickly set up. To do this, a wooden trim made of beams or rails with a cross-section of at least 10 cm is fixed to the load-bearing wall. For additional wind protection, screens made of reeds or brushwood are set up on the north side.

Standard frames measuring 160x106 cm make hotbeds simple and convenient to operate. They are successfully used for growing transplants, leafy greens, and cucumbers. When planting tomatoes, consider the height of the plants: place tall cultivars near the walls, and plant short ones closer to the center of the hotbed.

For maximum utilization of solar energy, install adjustable flat screens painted with white water-based paint. They create additional illumination through reflected light and increase the internal temperature by 2–3 °C. The paint coating on the screens is renewed as it wears out.

• Standard frame size — 160x106 cm
• Diameter of the trim logs — 10–14 cm
• Base pit depth — 70 cm
• Volume of soil per frame — 0.2 m³
• Manure combustion temperature — 50–60 °C

The hotbed trim is assembled from debarked, straight logs that ensure a tight fit of the frames. The south side of the trim is made lower than the north, and a special groove is cut on the south side for the frames to rest against. A trapezoidal pit in loose soil is reinforced with boards, while in clay soil it is left without lining. To avoid erosion by heavy rains, a drainage ditch is dug 0.5–1 m away from the hotbed, covered with wooden shields.

For heating, biological fuel is used — manure. First, it is piled into a heap and heated according to a specific technology.

1. Make several longitudinal grooves in the heap.
2. Pour one bucket of hot water into each groove.
3. Cover the mound with straw mats or thick burlap.

After 3–4 days, when the temperature inside the heap reaches 50–60 °C, the manure is moved to the hotbed. When laying it out, it is important to distribute the layers correctly to ensure uniform heat release. The manure is laid loosely, compacting it slightly only at the very edges of the hotbed. After 2–3 days, when the mass settles, a fresh portion is added.

Garden soil, turf soil, compost, or peat are used as nutrient-rich soil. After covering with soil, the hotbed is immediately covered with frames and mats made of straw, matting, or burlap for rapid heating. The frames themselves are assembled from wooden bars 7 cm wide and 6 cm thick, fastened with wooden dowels; 2–3 mm thick glass is installed, and the wood is coated with weather-resistant PF-166 varnish or drying oil.

Structures with boards and protection against adverse conditions

In the central and northern regions, single-pitch and double-pitch hotbeds with wooden boards are used to obtain early produce. A pit 0.5–0.6 m deep is dug for them, posts are driven in at the corners and the center of the long sides, and double boards are attached to them. The double construction (inner boards horizontal, outer vertical) holds heat reliably. Hooks for buckets are attached to the northern board, and along the northern and southern boards, support bars with a cross-section of 4.5x4.5 cm are mounted with 2.5–3 cm thick planks, which serve as a sturdy bridge for working with plants.

Frames for such hotbeds are made from light slats 5 cm wide and 3 cm thick, attached with hinges to the high northern board. After packing with manure and installing a thermometer, polyethylene film is stretched over the frames. To prevent windage and damage to the film by wind, a special installation technology is used.

1. Tightly stretch twine or fishing line in several rows on both sides of the frame and secure them with nails.
2. Clamp the film between these rows of stretched twine.
3. Secure the film and twine from above with wooden laths.

In the open position, the frame is held by wooden supports inserted into brackets. In windy weather, the frame is secured against overturning with a strong rope tied to metal loops on the frame and the southern board. For ventilation, the frame is opened slightly, and in case of temperature fluctuations (hot day and cold night), a gap of 2–4 cm is left between the frame and the board.