How to Grow Hydroponic Tomatoes

Hydroponic tomatoes are grown in a nutrient solution rather than soil. Growing tomatoes hydroponically allows the grower to raise them in a controlled environment without weeds, insects or soil-borne diseases. Hydroponic systems recycle water and nutrients, and optimize space. Hydroponic tomato plants grow faster than soil-grown plants, and their yield is greater.

1. Raise your tomato plants from seed. If you bring plants in from the outdoors, you will introduce pests and diseases. Start seeds in a nursery tray with a rock wool starter. Soak the rock wool and adjust the pH to 4.5 before adding the seeds. Put on the domes.
2. Place seedlings under a metal halide light source for 12 hours per day as soon as they sprout. Take care not to let the light shine on the roots because this can damage them.
3. Transplant seedlings into the hydroponic system. Wait until their roots start to protrude from the bottom of the nursery tray. You can move the plant and the rock wool together.
4. Grow tomato plants in individual pots. Fill the pots with haydite (a reusable, porous rock) and connect them to an automatic drip-irrigation system. You can also place the plant and rock wool into holes spaced about 1 foot (30 cm) apart in a trough of rock wool.
5. Feed the tomatoes. Drip water and nutrients into the pots or trough during the hours when the light source is on. Mature plants need 4 quarts (liters) per day. Change the nutrient solution every week.
6. Expose growing plants to between 16 to 18 hours of light a day. Then turn off the lights and let them sit in total darkness for about 8 hours.
7. Maintain pH level between 5.8 and 6.3 for growing tomato plants. Adjust the pH levels as needed. Use phosphoric acid to lower the pH or potassium hydroxide to raise it.
8. Control the temperature. During "daylight" hours, the temperature should be 65 to 75 degrees Fahrenheit (18 to 24 C). At night it should be 55 to 65 degrees Fahrenheit (12 to 18 C). Use thermostats and fans to regulate the temperature. Fans also allow for air exchange.
9. Stake and pruning the tomato plants. Tomato plants need support to grow upright, but they are somewhat fragile. Prune them by breaking off stems with your hands rather than cutting them off. Use plastic ties that won't damage the plants when staking.
10. Pollinate the tomato plant blossoms. Touching a soft paintbrush to the pollen and then touching the stigma of the flower. Do this several days in a row as soon as you can see the stigma.
11. Leach the pots when changing the nutrient solution. This is necessary to wash out salt buildup around the roots.

Source