vegetable, ornamental, fruit, and berry crops cultivated in hothouses. Hothouse plants yield a crop during periods when outdoor cultivation is impossible. Vegetables raised in hothouses include cucumbers, tomatoes, and—to a lesser extent—peppers, lettuce, Chinese cabbage, cauliflower, spinach, dill, radishes, onions, celery, and parsley. The most common melon species raised in hothouses is the muskmelon. Ornamental hothouse plants include chrysanthemums, pinks, callas, cyclamens, stocks, hydrangeas, cinerarias, and primroses. Lemons, peaches, strawberries, grapes, and mushrooms (champignons) are sometimes raised in hothouses. Special varieties and hybrids of the above-mentioned crops are developed for hothouse cultivation.
Methods of cultivation include sowing seeds in the ground or on benches (radishes, dill), planting seedlings (cucumbers, tomatoes), maturing (cauliflower), and forcing (celery, onions grown for greens). There are a number of accepted crop rotations, making possible several harvests in the course of a year. Vegetables are cultivated as independent crops or as fillers, that is, plants sown or set out between rows of the principal crop. Glass-enclosed winter hothouses in the Central European USSR yield 28 kg of cucumbers (principal crop) and 1 kg of Chinese cabbage (filler) per sq m in the first rotation, 24 chrysanthemums per sq m in the second rotation, and 8 kg of green onions per sq m in the third rotation. Another standard crop rotation yields 18–20 kg of cucumbers per sq m in the first rotation and 7–8 kg of tomatoes per sq m in the second rotation.
Hothouse plants are grown in soil or, less frequently, in nutrient solutions (seeHYDROPONICS). Crop care involves the maintenance of good lighting and optimal air and soil temperature and humidity, the application of inorganic and organic fertilizers, and the control of pests and diseases. Crops are harvested continuously, as the various plant organs—the fruits, leaves, or heads—become commercially accepted. Hothouse cultivation makes use of the latest achievements in science and engineering and is highly industrialized.
REFERENCESSee references under HOTHOUSE.
G. V. BOOS