How to Grow Hydroponic Basil

Basil (Ocimum basilicum) has long been grown as a kitchen herb that adds flavor to Italian, Thai and Mediterranean dishes. It is hardy in U.S. Department of Agriculture plant hardiness zones 4 through 10, but it's cold-sensitive and is commonly grown as a garden annual harvested when the weather turns cold. To give your basil a boost, try growing it in a simple hydroponics system, indoors or out. Compact cultivars of basil such as "Bush" or "Spicy Globe" make fragrant and attractive houseplants without needing a lot of room.

To make a hydroponic raft system to grow basil in your yard, start with a "pond" made from a child’s wading pool, a plastic-lined wooden frame or any other clean, leak-proof container at least 8 inches deep. Cut a piece of 1-inch-thick polystyrene foam about an inch smaller than the dimensions of the pond. Buy some inexpensive net pots from a hydroponics supplier, and cut rows of holes through the polystyrene that will let the pots reach into the water without slipping through. The holes should be about 12 inches apart. Use an aquarium air pump to oxygenate the water for best results.

Create an indoor hydroponics system with a plastic storage tote that is at least 6 inches deep. Either cut a piece of polystyrene to fit inside and float freely, or use the bin’s lid as a support. Use net pots for the basil; cut holes in the foam or lid to hold the pots with the tops above the surface and the bottoms reaching into the water. Add an aquarium pump with an air stone attached to oxygenate the water and provide air to the basil roots.

Place your hydroponic system in a location that gets strong sunlight at least six hours per day. If you don't have a good area available, add artificial light such as a 4-foot-long double fluorescent light hung just above the basil. Fill the pond with water, and add nutrients. Buy a basic ready-made solution from a hydroponics store and add the nutrients to the water according to the label. If you prefer, mix water-soluble 20-20-20 fertilizer that includes micronutrients into water at the rate of 2 teaspoons per gallon. Add 1 teaspoon of Epsom salts per gallon and stir well. Float the raft on top of the mixture.

Set a cube of pre-soaked rock wool in each net pot and fill in around it with perlite. Place one net pot in each hole in the raft, making sure the rock-wool cube touches the water but is not submerged. Sprinkle a few basil seeds on each rock-wool cube. Once the basil germinates and the roots touch the water, plug in the aquarium pump so that the air stone fills the water with bubbles all the time. Thin the plants to one per cube, and begin harvesting as soon as they are large enough -- as early as four weeks after planting. Add water and fertilizer to keep the solution at least 5 inches deep at all times.