Indoor hydroponic tomato gardening is a method of growing plants year round in a water environment. This method increases tomato fruit production since the plants grow year round instead of only during the summer months. Control the tomato fruit size and growth rates by providing the proper water nutrient concentration rate in the hydroponics system. Choose dwarf or small plant size varieties to allow proper air circulation between the plants.
Start tomato seedlings by soaking 1-inch rockwool cubes for two hours in a planting tray filled with water. Drain the water from the tray and sow one tomato seed into each cube at a depth of 1/4 inch. Cover the tray with clear plastic and set it in a warm area with indirect sunlight.
Uncover the growing tray once tomato sprouts appear. Monitor the moisture level and add water to the tray as needed to prevent the cubes from drying out. Grow the tomato seedlings until the first set of true leaves appears in 10 to 14 days.
Assemble the hydroponics system of choice according to the manufacturer’s instructions once the tomato seedlings reach a height of 3 to 4 inches. Fill water into the system and turn it on to make sure the water moves through the tubing.
Test the water pH. Tomatoes grow best in a pH of 5.8 to 6.3. Add phosphoric acid to the water according to the package application rate to lower the pH or potassium hydroxide to raise the pH. Test the water pH each week for best results with tomato production.
Add hydroponics nutrients to the water according to the application rate for the volume of water in the system. The nutrients are the food source for the tomato plants. Add nutrients each time when adding water to maintain an appropriate concentration rate.
Transplant the tomato seedlings once they are 2 to 3 inches high. Set the small rockwool cube inside a larger rockwool cube that is set in the hydroponics system at a spacing of 10 inches apart. The rockwool cubes are a soil-less growing medium for hydroponics gardening.
Place metal halide grow lights over the tomato plants if the hydroponics system is set in a poorly lit area. Tomatoes grow best when given 10 to 12 hours of direct light each day. Place the grow lights 6 inches above the top of the plants and raise them as the plants grow.