Hydroponics is the agricultural practice of growing plants in water. Hydroponics systems are designed to allow the roots of plants to draw nutrients and moisture directly from a nutrient-rich water supply. Hydroponics encompasses several systems, including the water culture or lettuce raft, the drip system and the nutrient film technique.
One of the earliest known examples of hydroponics dates back to the Aztecs in Central America. The tribes on an island in Lake Tenochtitlan seeded rafts constructed from rushes and set them out into the lake. These island gardens floated on the water, the plants sending out roots into the nutrient-rich lake water. This basic system was non-mechanical, and required nothing more than seed, wood, rushes and patience.
The water culture system is similar in principle to the Aztecs' floating gardens. This system is sometimes referred to as a lettuce raft because greens do well using this method of hydroponics. Small holes are made in a piece of Styrofoam; the holes are for the pots with the seedlings. A container is filled with nutrient-rich water and the Styrofoam, with the potted seedlings, floats on the surface of the water.
The drip system is designed to allow the plant to sit within a tray, its roots suspended over a holding tank or reservoir of nutrient-enriched water. A pump pushes the water upward through a tube that feeds back into the tank. The enriched water bathes the roots, allowing them to take what the plant needs, and the rest return to the holding tank.
In the nutrient film technique, the enriched waters flow consistently over the root systems, dripped in from a reservoir. Again, the roots take what is necessary; the remaining liquids return to the reservoir.
In each hydroponics system, the plants are anchored by an inert medium. This includes clay pellets, gravel or rock, Rockwool and perlite. These materials contain no nutrients and serve only to hold the plant within the net pot.
A net pot is a cage-like container that allows the plant roots to grow outward and downward through the medium toward the water source.
Nutrients are directly mixed into the water source. This is the equivalent of fertilizing soil in a soil garden. The difference is the roots needn't expend energy burrowing through soil in search of food. The food is delivered to the plant roots.
Hydroponics systems are designed to give you control over the nutrient supply. You can consistently address each individual plant's needs. Additionally, hydroponics systems may be set up indoors, on patios or within greenhouses. Indoor hydroponics systems set up indoors may provide fresh produce year round.
The initial cost of a hydroponics system obtained through a retailer is likely higher than that of starting a soil garden. Sophisticated systems include lighting, pumps, tubing, net pots, growing medium, nutrients and reservoirs. One system may cost upwards of $200-$300 and accomodate two to three plants at a time. A first-time garden of six plants, then, may cost between $600 and $900.