Why Are My Tomato Leaves Spotted?
Spots on tomato leaves can be alarming, but their cause is not always the same. Brown patches that spread quickly in warm, wet weather may indicate tomato blight, while paler markings can reflect feeding or growing stress. Look closely, act promptly and improve the plants' growing conditions while fruit continues to develop.
Examine several leaves, including the newest and lowest, before removing anything. Tomato blight often begins as irregular brown patches that enlarge, sometimes with pale edges, and can be followed by dark marks on stems or fruit. It is more likely during warm, wet summer weather and can spread rapidly. Small pale areas without spreading may instead follow uneven watering, root stress or a nutrient shortage. Photograph the symptoms and note when they appeared, especially after prolonged rain. Check nearby potatoes as well, because potato blight can occur at the same time. Do not assume every spot is blight, but treat suspicious fast-spreading patches seriously and avoid handling plants while foliage is wet.
Remove affected leaves with clean secateurs, particularly those touching soil or showing clear spreading brown damage. Put the material in household waste or green waste if your local collection accepts diseased plant material; do not add it to a home compost bin where conditions may not destroy the problem. Disinfect secateurs between plants with hot, soapy water and dry them. Never strip a tomato plant bare in one session, because it still needs leaves to ripen fruit and avoid sun scorch. Remove a few leaves at a time, starting with the lowest and worst affected. Wash hands before moving to healthy plants, and clear fallen leaves from the soil surface.
Improve airflow around every plant. Tie indeterminate tomatoes securely to supports, remove side shoots if that suits the variety, and keep stems arranged so foliage is not bunched together. In a greenhouse or polytunnel, open doors, roof vents and side vents on suitable days to reduce humidity. Outdoors, avoid allowing plants to sprawl through dense vegetation. Water the soil at the base in the morning rather than wetting leaves late in the day. A 3 to 5 cm mulch of garden compost helps keep moisture even and reduces soil splash. Good airflow cannot cure blight, but it reduces prolonged leaf wetness and makes other spotting problems less likely.
Where summers are regularly wet, grow at least some tomatoes under cover. A greenhouse, polytunnel or simple rain shelter keeps rain from sitting on foliage while still allowing fresh air to move through. Do not shut a structure tightly on warm days, as humid stagnant air is also unhelpful. Use clean supports and fresh peat-free multipurpose compost for container plants, with drainage holes that remain clear. Space pots so leaves do not overlap heavily. In the garden, choose a sunny site that catches a breeze and rotate tomatoes away from last year's tomato or potato bed where possible. Cover-grown plants still need regular checks, because symptoms can arrive on air currents.
If spotting seems linked to pale leaves, poor growth or fruiting stress rather than rapid brown spread, review watering and feeding. Tomatoes in pots dry quickly in hot weather, while those in cold, saturated compost cannot use nutrients well. Water thoroughly when the upper compost is drying, then let excess drain. Feed according to the label for a suitable tomato fertiliser, without doubling the amount in an attempt to correct symptoms quickly. Make sure containers are large enough for the variety and have not become root-bound. In beds, work garden compost into the soil before planting. Improvement takes time, so judge new growth rather than expecting marked leaves to become green again.
Monitor plants twice a week until the crop is finished. If suspected blight reaches stems or fruit, harvest sound fruit that is nearing maturity and clear badly affected plants promptly to limit further spread. Do not save seed from seriously affected plants. In future, choose a site with good ventilation, start with healthy plants and avoid watering foliage. A dry summer may bring little trouble, whereas a wet season can make blight difficult even for careful gardeners. Keep a note of the variety, growing place and first symptoms. That record helps you decide whether covered cultivation, wider spacing or a different variety is most worthwhile next year.
Frequently asked questions
Should I remove every spotted tomato leaf?
No. Remove leaves that are clearly diseased, badly damaged or touching the soil, but retain enough healthy foliage to feed and shade the fruit. Taking too much at once weakens the plant and can expose tomatoes to scorch. Work gradually, using clean secateurs, and watch whether new spots continue to appear.
Can I eat tomatoes from a plant with blight?
Use only sound, undamaged fruit and discard fruit with brown, rotten or sunken patches. Harvest nearly ripe healthy fruit early if blight is spreading rapidly, then allow it to finish colouring indoors in a dry place. Do not store damaged fruit with good fruit, as decay can spread quickly in the bowl.
Why do lower tomato leaves spot first?
Lower leaves are closest to damp soil and receive the least airflow, so they are often first affected by splashing, humidity and ageing. Removing leaves that touch the ground and applying a mulch can help. However, blight can spread upwards, so inspect the whole plant rather than assuming the issue is harmless ageing.
General guidance for UK home gardens and allotments. Conditions vary by region, soil and season; the RHS or a local garden centre can give site-specific advice. Page updated 19 Sep 2026.