The word hydroponics comes from two green words: hydro, which means water, and ponic, which means to toil. Though growing plants hydroponically is not a new concept, in recent years the practice of growing plants in a nutrient solution instead of soil has become widely accepted. Plants grown hydroponically have a lower instance of disease, grow taller and produce more fruits and vegetables.
Determine the type of hydroponic system that you wish to use to grow the plants. Tomato, pepper and cucumber plants need to be grown in a substrate hydroponic system that includes a support medium such as perlite or rockwool to buttress the growing roots. Lettuce or herbs can be grown in a bare-root hydroponic system in which the plant is supported by a slab tray and roots hang suspended in a liquid chamber such as a hydroponic flood tray.
Germinate the plant seeds by placing them on a paper towel under a grow light and soaking the paper towel with water. Keep the paper towel damp and the seeds under the light until the seeds germinate.
Place the seedlings into a cube of rockwool growing medium to allow them to grow. Poke a hole into the center of the medium, place the plant into the hole and gently cover the exposed roots with the rockwool.
Water the plant with a solution of water and nutrients to help the plant grow.
Transplant the entire cube into a larger cube of growing medium as the seedlings outgrow the cube of rockwool. Dig a hole large enough to accommodate the cube in the center of the larger growing cube. Place the smaller growing cube into the larger cube.
Transfer the plants to their final containers when they no longer are considered seedlings. For a substrate system, this means digging a hole in the perlite or rockwool substrate and placing the entire block of rockwool directly into the substrate. For a bare-root system, gently wash away the rockwool from the roots, being careful to not damage the roots. Place the plant into a bare-root hydroponics device so that the roots are suspended in the liquid chamber and the plant is supported above.
Fill the root system chamber with a premixed, liquid-nutrient solution such as 3-15-27.
Change the nutrient solution every two weeks when the plants are small and weekly once they grow larger.
Check the pH of the nutrient solution daily. If the pH of the nutrient solution rises above 7.0, add a small amount of sulfuric acid. Large plants such as tomato vines may need daily applications of acid to keep the pH of the nutrient solution balanced.