An excerpt from a Honolulu Star-Bulletin article by Suzanne Tswei found here.
Growing vegetables the old-fashioned way in dirt is easy enough, but growing them in water is even easier. The veggies taste just as good, and nothing gets dirty.
Matsuo Okamoto, who has been teaching Hawaii's students how to grow vegetables for 45 years, has modified hydroponic methods for home gardeners. His procedures do not require expensive equipment, and are simple to follow.
"Just use recycled metal cans. You can grow a lot of lettuce -- and everybody eats lettuce -- in those cans," Okamoto said.
Okamoto recommends starting the garden with herbs and leafy greens, such as lettuce and Asian vegetables. They grow fast and have fewer problems with pests. If you want to grow tomatoes, green beans, bell peppers and other larger plants, you'll need bigger containers and more room. They require a trellis, attract more pests and take longer to mature.
The directions here are for growing leafy greens and herbs. Here are the materials you'll need:
1) 3-inch or 4-inch plastic pots for the plants. Drill a small hole in the side of each pot, about an inch below the top rim. Use a leather hole punch or pound a nail through the pot to make the hole.
2) Potting soil. The growing medium must be sterile, but the quality of the soil does not matter. The cheapest soil will do since nutrients for the plants are fed through the water.
3) Vegetable seeds or seedlings. It's best to purchase local seeds, such those produced by the University of Hawaii or Honolulu Seed Company.
4) Recycled cans or plastic containers. Okamoto recommends one-gallon metal coffee or food cans, which are free from school cafeterias and restaurants.
5) Thin plywood or other rigid material to use as covers to keep mosquitoes out. Cut the plywood to fit over the cans, drill a center hole to hold the pot. The hole should be 1/4" smaller than the pot. For example, for a 3-inch pot, the hole should be 2 3/4 inch.
6) Tap water
7) Miracle-Gro
Choose a location with lots of sun light. Place the cans on a flat surface on the ground or table tops so you won't have to bend over to work.
Follow directions on the seed package for planting each vegetable, otherwise here are the general directions to maintain your hydroponics garden:
1) Plant one or two seeds or seedlings in each pot. Make sure there's a small hole in each pot to allow the plant to breathe.
2) Fill the can with water, not to the rim but up to the top ridge. Mix in one teaspoonful of Miracle-Gro, stir well.
3) Fit the pot into the can cover, and place the cover and pot over the can filled with water. The bottom of the pot should be covered by 1/4-inch of water.
4) Leave the new plant undisturbed for one-and-half to two weeks. Afterward, check the water level every few days, making sure that the bottom 1/4 inch of the pot is still soaked in water.
5) After two weeks, the plant will start to use more water. Okamoto recommends changing the water once a week. Throw out the remaining water each week, using it to water plants in the ground. Fill the container with water and fertilizer, following previous directions.
6) Harvest when the vegetables are mature.