If seedlings befome too crowded in a hydroponic grower, they will compete with each other and not grow very well.
Plants can to thinned when they are a few inches tall. The extra plants can be removed and discarded, or, if not damaged, can be transplanted into another grower.
As a general rule, when the plants are a few weeks old, the grower can be thinned to keep only as many plants as you believe will fill the container. For a bucket container, this will probably be a few lettuce plants, or one bean plant.Transplanting
Most seeds have enough nutrient in their seed to last a week or two. After that they must get their nutrient from the outside environment. In hydroponics that means nutrients have to be supplied in the water.
When the roots are kept warm, (72 degrees F) seedlings are more able to take up nutrients from the water.
When a seedling is 2 to 3 inches tall, it is ready for transplanting into a larger container. A hydroponic grower can be created for the seedlings that will provide for root room for them to mature and produce food.
There are many types of containers that can be used for growing out plants. Experiment #1 provides the information on the needs of a simple grower.
Transplanting a seedling can be very stressful on the plant. Take care to get all of the roots and to loosen the media around the plant before moving it.
Some plants such as corn, snow peas and carrots do not transplant well, and they should be started from seed in containers that they will keep throughout their whole lives.
A seedling, when transplanted into a bigger growing unit, is stressed at first. In most cases, it will help the plant survive if you spray it with nutrient water. The plant can also absorb nutrients through its leaves as well as its roots, so the leaves can keep the plant nourished until the roots get settled.
When seedlings in seedling tray are about 2 to 3 inches high they are ready for transplanting.
Revised: 1 May 2016