Yellowing of Leaves in Hydroponics

Nutrient Deficiency

• Since hydroponic plants do not receive nutrients from the soil, they require gardeners to mix nutrients with the water they receive at their roots to keep them healthy. One of the advantages to hydroponic growing is that nutrients are delivered directly to the roots of the plants. Yellow leaves indicate a nitrogen deficiency that can be corrected with the addition of fertilizer or nutrient mix to the hydroponic growing environment.

Light Levels

• Hydroponic systems are frequently indoor systems kept in greenhouses so that the temperature and light can be controlled more easily. However, hydroponic plants that are kept out of the right type of light will develop weak, yellow leaves that do not process nutrients as well and stunt the overall growth of the hydroponic plant. Hydroponic plants grown indoors should have access to natural light or artificial grow lamps that provide light on the proper spectrum for growth.

Pests

• Whiteflies are a greenhouse pest that can go unnoticed without regular observation of the plants. Whiteflies feed on the undersides of hydroponic leaves, which makes them almost invisible unless the plant's leaves are disturbed. As whiteflies feed, they suck nutrients from the leaves of the hydroponic plant, which leads to yellow, wilting leaves and weak overall growth. Treat hydroponic plants with a mild pesticide to control the presence of whiteflies and other pests, including aphids, that may attack hydroponic plants.

Disease

• Hydroponic plants are susceptible to some diseases that cause yellowing of the leaves. The disease type is dependent on the plant; for example, hydroponic tomatoes are susceptible to late blight, a disease that is caused by fungi and spreads from unhealthy to healthy plants by way of spores. Keep track of the yellowing leaves on hydroponic plants to see if they develop fungal spots. Treat infected plants with a fungicide and remove severely damaged leaves.