Pushing your cart down the produce aisle in the grocery store, you may come upon tomatoes labeled ''hydroponically grown.'' Hydroponic plants do not grow in soil. The roots find their home in water or an inert, solid medium such as vermiculite or sand, which serve merely to support the plant.
A hydroponic setup can be put together at home with a wide-mouth jar filled with a nutrient solution, a stopper, and an aquarium aerator. The stopper needs two holes, one for a tube from the aerator and a larger hole for the plant's stem. Wedge some cotton in the larger hole to keep the plant from slipping down into the drink. Wrap the jar in aluminum foil to exclude light.
To grow plants in an inert, solid medium, you need two watertight containers with spouts at their bottoms joined by a flexible plastic hose. One container is for plants to grow in the medium. The other is for a nutrient solution. You must lift the container with the nutrient solution just high enough and just long enough to raise the nutrient solution around plant roots in the other container.
Raising and lowering a container of nutrient solution a half-dozen times per day (which might be needed for a rapidly growing plant) can get tedious. The process can be automated by having the nutrient reservoir set permanently below the plants, with a time-activated pump to feed the plants. Another way to get nutrient solution to the plant would be with a thick polyester rope wick. Put one end in a nutrient reservoir just below the plants and the other end up through the bottom of the plant container, with the rope's end unraveled and fanned out in the growing medium.
Make up a simple nutrient solution by dissolving a soluble fertilizer (look for a complete fertilizer with micronutrients) in water. Organic fish emulsion fertilizer is another option.
Some experimentation is needed to get the right nutrient balance to adequately nourish plants.
Off-color leaves are signs that a plant needs more fertilizer. Dry leaf margins indicate too much fertilizer. Needs will vary with the kind of plant being grown as well as growing conditions.
A gardener might want to try hydroponics because it's yet another fun way to fiddle around with plants. Those gardeners who are mechanically inclined might also like applying those skills to automating their hydroponic setups.
Commercially, the advantages of hydroponics are potential water savings and the ability to more completely automate plant care.
This article published in the Athens Daily News on Saturday, March 24, 2001.