How to Grow Tomatoes with Hydroponics

Updated February 21, 2017

Growing hydroponic tomatoes means growing tomato plants without soil. Hydroponic growing systems come in a variety of styles to suit every budget. This method of growing tomatoes is gaining popularity for its ease of use and elimination of soil borne diseases that many garden tomato plants are susceptible to. Tomatoes grow faster with the hydroponic method because the roots are not wasting energy trying to dig down for more nutrients and moisture.

Start the tomato seeds. Thoroughly soak hydroponic growing medium, such as rockwool cubes. Sow one seed in each cube. Place the cubes containing the tomato seeds in a grow tray available at many home garden centres. Cover the cubes with the tray's lid and place in a warm place where temperatures remain at least 21.1 degrees Celsius. Remove the lid and place tray under grow lights when seedlings sprout.

Transplant seedlings into a hydroponic growing container as soon as the roots are visible through the rockwool cubes, and three to four leaves appear. Keep seedlings under the grow lights for at least 12 hours per day.

Place the tomato seedlings 12 inches apart in larger rockwool planting cubes for adequate room to grow.

Place the seedling tray over the nutrient water reservoir to allow the roots to grow into the nutrient solution. Determine the correct level of pH in the nutrient solution according to the hydroponic system manual. Mature tomato plants will consume up to 4 litres of nutrient solution daily. Change the nutrient solution once every week to prevent salt-clogged emitters.

Keep tomato plants under grow lights for 16 to 18 hours per day. Place the hydroponic system--along with the grow lights--in a warm location with temperatures remaining fairly constant at 21.1 degrees Celsius.

Pollinate the tomato plants. Take a battery operated toothbrush and place on each truss of the tomato plant to ensure pollination. The truss of tomato plants are the separate clusters of yellow flowers that bear the tomato fruit. Pollinate the plants at least every two days.

Prune each tomato plant as they grow to maturity. Cut off all shoots and suckers that take nutrients away from the main stem.


As tomato plants mature, they will need to be staked with string to support the growing weight.

Things You'll Need

  • Tomato seeds
  • Hydroponic growing medium, such as rockwool cubes
  • Growing tray with cover
  • Grow lights
  • Hydroponic system
  • Nutrient solution
  • Battery operated toothbrush
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About the Author

Rachel Turner has been writing professionally since 2000, focusing on gardening and home improvement topics. Her articles have appeared online at SlowTravel and in publications such as the "Arkansas Gardeners," "One Step Ahead" and "Writers Now." Turner holds a Bachelor of Arts in English from Arkansas State University.