Hydroponic systems grow plants without soil, instead using an inorganic growing medium that gives support without nourishing the plant. The nourishment comes from a specially formulated solution, which can be well controlled in quantity and quality. Nearly all vegetables and flowering plants can be grown using hydroponics. With dozens of growing mediums available, starting a hydroponic system can be an inexpensive way to get homegrown vegetables and flowers year-round.
Any seed can be grown in a hydroponic system. You can obtain seeds from your usual sources, such as local garden supply shops and seed catalogs. Whenever possible, use greenhouse varieties, as these will self-pollinate.
A more relevant question when starting a hydroponic garden becomes one of practicality. Which are the best plants to grow in a hydroponic system? Hydroponics Simplified recommends planting varieties that are expensive to buy at the store, such as lettuce and eggplant.
It is best to start a hydroponic system from seed. The roots of transplanted seedlings may carry diseases from the soil. Start hydroponic seeds in cubes of inorganic material, not peat or potting soil. Seeds sown directly into the planting bed may be washed away in the nutrient solution. Start seeds in a warm and brightly lit place and, when the plant is 2 to 3 inches tall, transplant the cube directly into the growing medium. After transplantation, be sure to keep your grow lamps as far above the seedlings as possible so that the seedlings are not burned. Gradually lower them every few days until they are about 24 inches above the plants.
Since saving money is one of the major reasons people choose to grow hydroponic plants, throwing out unused seeds seems impractical. Seed packets usually come with more seeds than you'll use, and the leftovers will remain viable for three to four years. Hydroponics Simplified recommends tightly closing the package and storing it in a jar in the refrigerator. Drop in some powdered milk wrapped in a tissue to keep the moisture levels right. If you save seeds, test them before use by placing them between two damp sheets of blotting paper. If they haven't sprouted in 10 days, don't use them.
Role of Growing Mediums
By definition, hydroponic plants grow without soil. Plants receive their nourishment through a nutrient solution that comes in direct contact with the roots. However, plants still require mechanical support to hold them upright, necessitating a growing medium. The plant does not receive any nutrition from the growing medium. Just about any substance, can act as a growing medium, but some are easier to work with than others. Choosing a growing medium depends on both purpose and preference.
Types of Growing Mediums
Coconut fiber consists of powdered coconut husks and is a byproduct of the coconut industry. Coconut fiber is an organic medium that holds water well, has a high oxygen capacity and offers some protection against root diseases.
Perlite also works well as a hydroponic growing medium, either by itself or with another medium, often vermiculite. Perlite does not hold water well, however, so the medium may dry out between waterings. Also, the dust from perlite is harmful, so be sure to wear a mask when handling it. As you become more advanced, you may want to mix perlite and vermiculite in a 1-1 ratio to achieve a better level of water retention.
Lightweight expanded clay aggregate, or LECA, is formed by superheating clay. It is also used in potted plants to improve soil drainage. LECA holds moisture well and has the added advantage of being reusable. Combing LECA and coconut fiber results in a medium that retains the right amount of water for hydroponic plants to grow.