Tomato Leaf Yellowing: Causes and Treatment Options

Yellowing of tomato leaves, known as chlorosis, can result from a range of issues including nutrient deficiencies (nitrogen, magnesium, potassium), inconsistent watering, heat stress, fungal diseases such as early blight or late blight, and normal aging of lower leaves as the plant redirects energy to fruit. Identifying the specific cause—whether it is over‑watering, soil pH imbalance, pest damage, or environmental stress—is essential before taking action.

Remedial steps include adjusting irrigation practices, applying appropriate fertilizers to address deficiencies, mulching to moderate soil temperature, and removing severely affected foliage when necessary. In many cases, simple changes can keep plants productive through the late season, while some yellowing is a natural part of the plant’s growth cycle.