Hydroponics is a method of growing plants in growing media or water without using soil. The system consists of pots or trays for the plants, a reservoir of nutrient solution, and tubes or channels to deliver the water to the plants.
Although hydroponics is an easy way to grow plants, problems do occur. Most problems can be solved quickly with no lasting damage to the plants. Concentrated nutrient solution, poor air circulation and poor water aeration are the main causes of problems in a hydroponic garden.
Prevent the roots and leaf tips of plants from burning due to concentrated nutrient solution by adding fresh water to the original fill line on the reservoir. Do not add any more fertilizer until it is time to change the nutrient solution.
Correct nutrient deficiencies by spraying plants with an all-purpose foliar fertilizer following the manufacturer's directions or change the nutrient solution every week instead of every two weeks. Alternatively, try another type of hydroponic fertilizer.
Younger leaves of plants lacking in iron turn yellow in between the veins. The older leaves of plants that are not receiving enough nitrogen turn yellow, and new shoots and roots are stunted. Phosphorous deficiency, a common problem in hydroponics, also causes stunted growth, and the foliage turns dark green tinged with red, blue or purple. Another symptom of lack of phosphorous is a small root mass. In addition to spraying with foliar fertilizer, use plastic mesh to raise the plants off the floor of the container to correct phosphorous deficiency.
Eliminate algae by aerating the water using opaque tubing and a dark colored reservoir, and covering holes in the reservoir with patches to keep out light. Remove algae and sterilize the system between plantings with a 10 percent bleach solution. Use 10 parts of bleach to 90 parts of water. Improve water aeration by installing an air pump with an air stone in the reservoir.
Prevent fungal diseases by decreasing the humidity, increasing the air circulation around the plants, and providing adequate venting. Treat fungal diseases with fungicide applied at the rate recommend by the manufacturer. Improve air circulation by propping the seedbed slightly higher above the nutrient solution or drill holes in the solution container just above the highest level of solution.
Eliminate pests by spraying with insecticidal soap following the manufacturer's instructions.
Avoid burned patches on plant foliage by moving the lights high enough so that the heat from the lights does not scorch the leaves.