Expand your vegetable harvest season by planting and growing vegetables in an indoor hydroponics system. Vegetables that grow well in the water environment are tomatoes, peppers and cucumbers. Plant the vegetable seeds eight to 10 weeks prior to planting in the hydroponics system to give the seedlings enough time to reach a desired size. Purchase a hydroponics system and supplies at a garden store or from an online retailer.
Soak 1-inch hydroponic rockwool cubes in a tray of water for two hours. Drain the water from the tray and sow one vegetable seed into each cube at a depth of 1/8 to 1/4 inch. Cover the tray and cubes with clear plastic and place it in an area that receives indirect sunlight until the seeds sprout.
Remove the plastic covering once the sprouts appear and move the tray to a sunny area. Monitor the rockwool cube moisture to make sure they do not dry out. Grow the vegetable seedlings until they reach a height of 2 to 3 inches.
Transplant the vegetable seedlings after the first set of true leaves are visible on the seedlings. Set up the hydroponics system and add nutrients to the water based on the package instructions for the water volume moving through the system.
Transplant the rockwool cubes with seedlings into the hydroponics system by placing the 1-inch cubes inside larger cubes that fit into the system. Space the hydroponics growing containers 6 to 8 inches apart for small plants like peppers and 10 to 12 inches apart for large or bushy plants like tomatoes.
Monitor the amount of water in the hydroponics system and add more as needed. The water level will decrease from plant consumption and evaporation. Add nutrients to the water each time when adding water to the system to maintain an appropriate concentration for plant growth.
Assemble grow lights over the plants if the hydroponics system is in a poorly lit indoor area. Vegetable plants grow best when provided bright light for several hours a day. Place the lights 6 inches from the plants and raise the lights as the plants grow taller.