Long popular with commercial growers, the science of hydroponics is increasingly popular with home gardeners. It is, essentially, the science of growing food crops in a soilless growing medium, primarily in a greenhouse. Plants get their nutrients from a nutrient-rich, water-based solution that is circulated around their roots. Hydroponically grown vegetables are less susceptible to soil-borne diseases than field-grown vegetables and can be grown virtually any time of the year in a climate-controlled greenhouse.
Widely grown commercially, tomatoes (Lycopersicon lycopersicum var.) produce well when grown hydroponically. The key is to choose varieties shown to produce well when grown without soil and/or in a greenhouse environment. Tomato varieties that can be pruned to a vinelike plant, also called "indeterminate" tomatoes, are the best choice for growing hydroponically. Varieties of indeterminate tomatoes, such as 'Trust', 'Quest' and 'Blitz', grow and produce the most fruits in the controlled conditions associated with hydroponics.
Cucumber varieties grown hydroponically in the United States are primarily gynoecious European greenhouse varieties (Cucumis sativus var.). This type of cucumber produces only female flowers and does not require pollination to set fruit. The most widely grown varieties are 'Sandra', 'Toska 70', 'Farbio' and 'Corona', due to their resistance to diseases. They produce dark green, seedless cucumbers that are 12 to 14 inches long and weigh about 1 lb. Mildly flavored, their thin, tender skin does not require peeling.
Traditionally imported to the Unites States from Canada, Israel, Spain and the Netherlands, high-quality, hydroponically grown, red, yellow and orange bell peppers (Capsicum annuum var.) command high prices at the retail market. Growers in the United States are increasing production of these crops in response to high demand from consumers. Wholesale prices of hydroponically greenhouse-grown, colored peppers are three times that of field-grown, colored peppers shipped to the Miami area, according to the University of Florida Extension. The best red sweet pepper varieties for hydroponic cultivation in greenhouses are 'Torkal' and 'Triple 4'. For peppers that mature to orange, choose the varieties 'Lion' or 'Paramo'. The best varieties of yellow bell peppers for hydroponic production are 'Kelvin' and 'Bossanova'. In a greenhouse with controlled temperatures, hydroponic production of these peppers is possible year-round.