What are the white or tan papery patches appearing on my leaves during a heat wave?
White or tan dry patches on the upper surface of sun-exposed leaves are heat scorch — the leaf tissue has been killed by a combination of excessive temperature and direct solar radiation.
Heat scorch shows as irregularly shaped white, tan, or pale brown patches on the upper surface of leaves that were facing the sun. The affected tissue is dry and papery — not water-soaked or mushy — and the damage is sharply confined to the exposed areas. The undersides of the same leaves often look normal. Large, thin-leaved plants like squash or bean tend to show more visible damage than small-leaved herbs. Scorch often appears suddenly after a day or two of extreme heat above 95°F, especially when the temperature spike follows a run of milder weather.
Leaf cells die when their temperature rises above the threshold at which proteins denature — typically around 104–113°F at the cellular level, which is easy to exceed in direct sun during a heat wave even when air temperature is lower. Plants that have been growing in partial shade and are then suddenly exposed to full sun are especially vulnerable, as their leaves haven't adapted to high light intensity. Moisture stress compounds the problem: a plant struggling to pull enough water can't cool its leaves by transpiration as effectively, so leaf temperatures spike faster. Young transplants and recently pruned plants with newly exposed interior foliage are common casualties.
There is no recovery for tissue that has already been scorched — those patches are dead and will remain. Remove severely damaged leaves that are more than half affected, as they become entry points for fungal infection. Provide shade cloth (30–40% shade) during extreme heat events if you can; row cover draped loosely also cuts temperature significantly. Water deeply in the morning to ensure plants have maximum moisture available before peak afternoon heat. Avoid overhead irrigation during the hottest part of the day — water droplets on leaves during intense sun can sometimes focus heat, though this is less of a factor than overall moisture stress.
Once temperatures moderate, the plant should push out new healthy growth from unaffected tissue. If scorch was limited to a portion of the canopy, yield is often not significantly affected. Plants that were already under drought stress before the heat event take longer to recover. If scorch was severe and defoliation was extensive, expect slowed fruit development for several weeks as the plant rebuilds photosynthetic capacity.
- AphidSoft, clustered insects on new growth causing curled leaves and sticky honeydew.
- Black RotV-shaped yellow lesions at brassica leaf margins with blackened veins inside — a bacterial disease that moves through the vascular system.
- Blossom DropFlowers fall before setting fruit, often during temperature extremes or after weather stress.
- Gray Mold (Botrytis)Gray-brown fuzzy mold on fruit, flowers, or stems — soft, collapsing tissue beneath the coating in cool, wet conditions.
- Brown Marmorated Stink BugSunken, corky dimples on fruit and pods caused by a mottled brown shield bug feeding through the skin.
- Why does my tomato or pepper have a white or pale papery patch on the side of the fruit?White or tan papery patches on the shoulder or side of a tomato or pepper are sunscald — the fruit tissue has been killed by direct sun exposure, often after the plant lost foliage cover.
- What does drought stress actually look like, and how do I know when to water versus when something else is wrong?Drought stress progresses from midday wilting to all-day wilting, leaf curl, and eventually aborted fruit and flowers — the key is catching it before the plant has been dry long enough to abort reproductive structures.
- My tomatoes wilt every afternoon in hot weather — is something wrong?Midday wilt on hot days is often a normal, temporary response to heat load — if plants recover by evening, the roots are functioning and the wilting is a water conservation mechanism, not distress.
- We're in a drought — how do I keep my garden going?Mulch, deep infrequent watering, and cutting back on what you're growing are the three adjustments that make the biggest difference during drought conditions.