Guides
Why are my plant leaves curling?
Leaves curl for several reasons: heat, drought, pests, weedkiller drift, viruses and root problems can all distort them. Look first at whether the curling is on new growth or older leaves.
Check new growth first
Curling on the newest leaves and shoot tips points to pests, mites or weedkiller drift. Curling on older leaves points more often to water and heat. If curled leaves are stuck together with silk, unroll one and check for an insect inside.
Work down the list
Aphids on the shoot tips
- What you would see
- Newest leaves curled, puckered and often sticky, with the curl tightest where the growth is youngest.
- The check
- Unroll a curled leaf and look underneath. Aphids feed on the underside and the leaf grows unevenly around the damage, so the insects are inside the curl rather than on top of it.
Heat and drought
- What you would see
- Leaves rolling inwards along their length on a hot day, worst in full sun, easing as the evening cools.
- The check
- Feel the compost and look again after dark. Rolling reduces water loss from the leaf surface. If the plant unrolls overnight, it is coping with heat rather than failing.
Tomato leaf roll
- What you would see
- Lower leaves of a tomato rolling upward into tubes, firm and green, on a plant fruiting normally.
- The check
- Look at the colour and the crop. Rolled leaves that stay dark green on a healthy plant are usually a response to heat, heavy watering or hard side-shooting. The fruit is unaffected, and no treatment is needed.
Weedkiller drift
- What you would see
- Growing tips twisted, leaves cupped, narrowed or fan-shaped, stems bending, and tomatoes worst of all.
- The check
- Think about what happened upwind, and about your compost. Hormone weedkiller drifts a long way in warm weather and survives in manure and grass clippings, so the source is often nowhere near the plant.
Peach leaf curl
- What you would see
- Peach, nectarine or almond leaves thickened, blistered and puckered, flushed red and white, from the moment they open in spring.
- The check
- Note the month and the host plant. Red, swollen, crumpled peach leaves in April usually mean peach leaf curl. The infection happened in the wet weeks before the buds opened.
Leaf-rolling caterpillars or sawflies
- What you would see
- Individual leaves rolled into neat tubes or folded and spun shut with silk, with the rest of the plant untouched.
- The check
- Unroll one. A caterpillar inside a silk-lined roll is usually a tortrix or a leaf-rolling sawfly. On a garden plant, picking off the rolled leaves is usually enough.
Broad or cyclamen mites
- What you would see
- Only the newest leaves affected, hardened, thickened, brittle and curling downward, with growth stalling and nothing visible on them.
- The check
- Look for the damage rather than the mite. Broad and cyclamen mites are hard to see without a lens and distort only the growing point. Clean older leaves with badly distorted new leaves point to them.
Root damage
- What you would see
- Curling and cupping on a plant whose compost is wet, with lower leaves yellowing and growth stopped.
- The check
- Slide the plant out and smell the root ball. Rotted roots cannot supply enough water, so the leaves curl much like they would in drought.
A virus
- What you would see
- Curling and distortion combined with mottling, yellow streaking or a ring pattern, on a plant that never grows out of it.
- The check
- Watch it over a fortnight. Damage from an insect or a chemical usually stops with the affected leaves. A virus keeps producing distorted growth.
Capsid bugs
- What you would see
- Young leaves ragged with small brown-edged holes as well as puckered and curled, on fuchsias, dahlias, currants and apples.
- The check
- Look for the holes inside the distortion. The bug feeds on the tiny leaf before it expands, so a pinprick becomes a ragged hole and the leaf grows crumpled around it.
Frost damage on soft new growth
- What you would see
- New growth curled, puckered and browning at the edges after a clear night in spring, on the exposed side of the plant.
- The check
- Check the date against the weather. Frost damage appears all at once and then stops spreading. Pest, disease and root problems usually keep developing.
Still not sure which one it is? Photograph the leaf and compare it against the full library.