Hotbed

hotbed, low, glass-covered frame structure for starting tender plants. It differs from a cold frame only in that the soil is heated—either artificially as by underground electric wiring or steampipes, or naturally with partially fermented stable manure, which is mixed with dead leaves or straw, placed in the bottom of the hotbed frame, and covered with a layer of soil. Heat is produced by the decaying organic matter. Proper ventilation is important, as is thermostatic control of artificially heated hotbeds. Tomatoes, cucumbers, celery, and other crops can be grown in hotbeds in the spring.

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hotbed

a glass-covered bed of soil, usually heated by fermenting material, used for propagating plants, forcing early vegetables, etc.

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hotbed [′hät‚bed]

(agriculture)

A bed of soil enclosed by a low frame with glass panels and heated by fermented manure or electric cables; used for forcing tender plants to grow out of season or to protect tender exotic plants.

(metallurgy)

An area where hot-rolled metal is placed to cool. Also known as cooling table.

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hotbed

A small low enclosure heated by fermented manure or electric cables and usually covered with glass; used for forcing bedding plants and vegetables to grow out of season or for protecting tender exotics.

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Hotbed 

a structure for starting vegetable and flowering plants and for raising vegetables and seeds. Hotbeds are commonly used in countries located at northern latitudes above 40°. There are two types of hotbeds: single-pitched and double-pitched. Both types may be sunken or aboveground. Above-ground hotbeds may be stationary or portable. The heating source may be solar, biological (biological fuels), or technological (water, steam, or electrical). In cold weather, hotbeds are covered with a glass sash or, less frequently, translucent film. Hotbeds may be used at various times during the growing season (early, middle, or late).

Sunken single-pitched hotbeds are essentially trenches covered with sashes. Such hotbeds usually are heated by fermenting vegetable substances. Less frequently, they are heated with water or electricity. Besides the trench and sash, a hotbed has a reinforced-concrete or wooden frame to ensure that the sash fits tightly and securely. Early-season hotbeds are used from late February to early March (in the central European USSR), mid-season hotbeds are first used in late March, and late-season hotbeds are used beginning in early April. The standard dimensions of hotbeds are 160 X 106 cm. Hotbeds with reinforced-concrete frames are common in the central European USSR and in the south. Hotbeds with wood frames last eight to 12 years, and those with reinforced-concrete frames last 20 to 25 years.

In northern regions characterized by swamps or permafrost, stationary single-pitched hotbeds are used. The structures are built aboveground, and no foundation pits are dug. The hotbeds and the spaces between them are filled with biological fuel.

Portable single-pitched aboveground hotbeds are constructed without foundation pits and have four to six sashes. Heated biological fuel is distributed on an area cleared of snow. The fuel is 50–60 cm thick for mid-season hotbeds and 30–40 cm thick for late-season hotbeds. The frame is placed above the fuel.

Double-pitched hotbeds are not widely used owing to the looseness of seams between the glass sashes set up on both sides of the hotbed. Exceptions are the Riga and Suzdal’ double-pitched hotbeds.

Before the construction of hotbeds, the site is leveled, and the distribution of the trenches is planned. Hotbeds are distributed within a rectangular area, with 30 standard-size hotbeds, or 600 sashes, in each area. The rectangular area is 72 m long and 21.2 m wide (equal to the length of a 20-frame hotbed). The end paths, measuring 10 m wide and running from north to south, prevent soil erosion. Paths measuring 15 m wide help conserve the biological fuel. Wide paths alternate with narrow ones. Paths between rectangles, running parallel to the hotbeds, are 5 m wide. Such a distribution of hotbeds makes possible the construction of 2,500 frames on 1 hectare. On farms using hotbeds heated by biological fuel, the hotbeds are arranged in strips leaving a path 2.5 m wide between every two hotbeds and a path 0.7 m wide between hotbeds.

Seedlings and hotbed crops are raised on various substrates (soil mixtures), which are spread over the biological fuel or on top of heaters.

REFERENCES

Boos, G. V. Ovoshchnye kul’tury v zakrytom grunte. Leningrad, 1968.
Rubtsov, M. I., and V. P. Matveev. Ovoshchevodstvo. Moscow, 1970.
Spravochnik po ovoshchevodstvu. Editor in chief V. A. Bryzgalov. Leningrad, 1971.

G. V. BOOS