There can be a variety of reasons why plants begin to turn yellow. From inadequate care to improper lighting to environmental toxins to pests and disease, the most important facet of troubleshooting the sudden appearance of yellowing leaves and stems is to do a thorough assessment of all potential causes before beginning a course of treatment. Here are some common reasons why some plants may turn yellow. Use this checklist to do an assessment of yellowing plants and determine the best course of action and treatment.
When plants do not receive adequate moisture, or are the recipients of overwatering, yellow leaves can be the results. In particular, overwatering or leaving plants in standing water can cause the roots to start to decay and fail to deliver nutrients to the plant extremities. Often there will also be an unpleasant odor emanating from the pots of plants that are being overwatered, which is a clue as to the possible cause of the appearance of yellowing leaves.
When plants are subject to overwatering, this causes nutrients to be leached out of the soil and a condition called Chlorosis, or yellowing leaves, can be the result. The correction is to apply fertilizer at a minimum of quarterly and correct moisture levels.
A lack of sunlight or overexposure to sunlight can also cause some plants to turn yellow. Some plants are very tolerant of a variety of light conditions while other plants have very specific requirements. Shade loving plants can be burned by exposure to too much direct light, while sun loving plants can wilt, droop, and turn yellow if adequate exposure to sunlight is denied.
Some pests and many fungal disease can cause yellowing of the leaves of susceptible plants. Investigate known issues with pests and fungus for the specific affected plant to determine treatment.