The best way to transplant into a hydroponic system is to grow your own seedlings in hydroponic growing medium. Commercial hydroponic growers plant their seeds directly into a rockwool cube. The rockwool cube containing the transplant is inserted directly into the growing medium of the hydroponic system. Plants grown in soil can be used if all soil is washed away from the roots before planting in the growing medium.
Using Loose Growing Mediums
Fill a small container with a moist hydroponic growing medium such as sand, vermiculite or perlite.
Punch a small hole in the growing medium and insert the seed. Cover the seed with moist growing medium.
Water the seeds gently with water only until the first true leaf appears. Do not use fertilizer or nutrient solution at this stage.
Water with 1/4- to 1/2-strength hydroponic nutrient solution once the leaves appear. Keep the growing medium moist, but not wet, until ready to transplant.
Transplant seedlings into the hydroponic system when the plant has several sets of leaves and is beginning to outgrow its container. For water culture systems, gently wash away the growing medium and place the plant into the net pot. Support the plant with toothpicks if necessary. In aggregate based systems, remove the plant from its container and insert it into the aggregate with its growing medium intact.
Growing Transplants in Rockwool Cubes
Soak rockwool cubes in water to moisten them. Insert one seed into the hole in a rockwool cube.
Water the seeds gently with plain water until the seeds germinate and the first leaves appear.
Insert the rockwool cube directly into the hydroponic system. Use 1/4- to 1/2-strength nutrient solution. Gradually increase the nutrient to full strength after two to three weeks.