Hydroponics is the process of growing plants without soil using nutrient-rich water to deliver everything the plant needs. Hydroponically grown plants grow faster and produce higher quality fruits and vegetables. Many of the plants we already grow are adaptable to hydroponics, but some do better than others. Both the home gardener and large scale food producers can use various techniques and scale them to the size that fits their individual needs.
Lettuce is quickly gaining popularity as a hydroponically grown vegetable. The turnover time from seed to harvest is 36 days. They can be produced for local markets in large quantities in greenhouses year-round in northern climates that would normally have a short growing season. Lettuce types such as romaine, butter, Boston and bibb do very well using the floating method, where sheets of foam are floated on 4-inch-deep pools. The roots are planted in net pots using an inert material such as rockwool and suspended through holes in the foam so they can reach the nutrient-rich water.
Tomatoes are another of the most popular types of hydroponically grown plants. They do not do very well in the floating method and preform better with an ebb and flow system that fills up, then drains several times an hour. They are usually planted in net pots filled with rockwool or other inert material, then placed in a bed of expanded clay balls. Unlike other food crops, tomato vines continue to grow even after they start producing fruit and must be supported by a trellis or wire. Fresh tomatoes can be produced all year in a climate-controlled greenhouse or under artificial lights, although pollination can become a problem. Indoor grown plants must be hand pollinated. Some greenhouse growers have started introducing cultured honeybees to help. Good tomato varieties for hydroponic production include Apollo, Belmondo, Caruso, Dombito, Larma, Perfecto, Trend and Trust.
Not all hydroponically grown plants are for food production. The home windowsill gardener can also grow beautiful orchids using what is called semihydroponics. In this method a deep translucent plastic pot without bottom drain holes is used. Instead, the drainage holes are located an inch above the bottom on the side of the pot. This allows for a reservoir of water to build up at the bottom, but the roots never get fully submerged. The potting medium is inorganic expanded baked clay pellets which absorb the water from the reservoir and transport it up to the top of the pot naturally like a wick. This provides nice even moisture distribution and plenty of air to prevent rotting. All the grower has to do is keep the reservoir full and let excess water drain out of the sides. Good candidates for this method are Phalaenopsis, Cattleya, Paphiopedilum and Cymbidium.