Why Are My Tomato Leaves Turning Yellow?
Tomato leaves turn yellow most often from watering problems, normal aging of lower leaves, nutrient imbalance, or a leaf disease. Start by checking which leaves yellow first and whether spots, wilting, or poor drainage are also present.
A few lower leaves yellowing as a tomato plant grows can be normal, particularly where older leaves receive little light. Remove yellow leaves that touch soil or are fully dead to improve airflow and reduce splash-borne disease risk. Do not remove large amounts of healthy foliage, since leaves support fruit development and help shade fruit.
Both drought and waterlogged soil can yellow leaves. Water deeply at the soil line, then allow the upper soil layer to dry slightly before watering again. Raised beds, organic matter, and mulch can help stabilize moisture, but mulch should not be piled against the stem.
Nitrogen deficiency usually appears first on older leaves as a more uniform pale green or yellow color. A soil test is the best way to determine whether nutrients are lacking or soil pH is limiting uptake. Add fertilizer only according to test recommendations and avoid excessive nitrogen, which can favor leafy growth over fruiting.
Yellow leaves with dark spots, concentric rings, or rapidly spreading patches may indicate fungal or bacterial leaf diseases. Keep foliage dry by watering the root zone, space and stake plants for airflow, mulch soil to limit splashing, and remove fallen leaves. Rotate tomatoes, peppers, potatoes, and eggplants away from the same bed for several years when disease has been recurring.
Wilting combined with yellowing can point to root trouble or a vascular disease. Inspect for poorly drained soil, root damage, stem injuries, and pests near the base of the plant. If one plant declines quickly while nearby plants remain healthy, remove it and seek a diagnosis through local Cooperative Extension rather than assuming it needs more fertilizer.
Prevent recurring yellowing by planting tomatoes in full sun in loose, well-drained soil, using clean supports, and selecting varieties with disease-resistance letters suited to common local problems. Keep a simple record of symptoms and weather. The pattern of yellowing, such as lower leaves versus newest leaves, often provides the most useful clue.
Frequently asked questions
Why are only the bottom tomato leaves yellow?
Older lower leaves naturally age first, but this pattern can also signal nitrogen shortage or an early leaf disease. Look for spotting and check whether the yellowing is spreading upward.
Can I compost yellow tomato leaves?
Leaves yellowed only by age or non-disease stress can generally be composted. Dispose of leaves with suspected blight, bacterial disease, or unexplained severe symptoms rather than returning them to the garden.
Should I fertilize a yellow tomato plant right away?
Not automatically. Correct watering or drainage issues first and inspect for disease. A soil test or clear deficiency pattern is a better basis for fertilizer than leaf color alone.
General guidance for US home gardens. Conditions vary by region and season; check with your local Cooperative Extension office for site-specific advice. Page updated Aug 4, 2026.