Skip to main content

Plant problems

My plant's leaves are curling

Short answer

Curling in the middle of summer is usually the plant shrinking the surface it exposes to sun and wind, and where that has been studied closely the rolling does no lasting harm. Check the soil at depth before anything else. If it is damp down there, look at the newest leaves for insects, then step back and check whether several unrelated plants are affected at once, which points away from a pest entirely.

Most likely causes

Listed in the order they are worth ruling out. It is normal for more than one of these to be happening at once, so work down the list rather than stopping at the first match.

  1. 1

    Heat, and soil that has gone dry

    Curling in the middle of summer is most often the plant reducing the leaf surface it exposes to sun and wind, not a disease. It is worth ruling out first because it is the cheapest thing to check and because the published guidance is that this kind of rolling does no lasting harm.

    What to check first

    Push a finger two inches into the soil in the middle of the afternoon. Dry at that depth points here. Still damp at that depth points at one of the causes below instead.

  2. 2

    Aphids or similar insects feeding on the new growth

    Check the softest new stems and leaf tips first. Aphids gather there in dense clusters rather than spreading evenly, and ants walking the stem are a second sign worth noticing. Photo by Josef Schlaghecken via Wikimedia Commons, CC BY-SA
    The curled leaf tip is where to look, and the ladybug is worth noticing too. Aphids feed on the softest new growth and the leaf curls around them, and a ladybug or its larvae working the same stem means the colony is already being eaten. That is a reason to wait rather than to reach for anything. Photo by Greyson Orlando via Wikimedia Commons, CC BY-SA
    This is the honest scale on a full leaf: a tight dark cluster tucked where the leaf meets its stalk, and almost nothing elsewhere on the leaf. Turn leaves over and check the joints, because the colony hides in the angles rather than spreading across the open surface. Photo by ML5 via Wikimedia Commons, CC0

    These insects work on the softest tissue, so the damage shows up as curled and puckered new leaves at the tips while older leaves lower down stay flat. That split, new growth distorted and old growth normal, is the useful signal.

    What to check first

    Turn over the newest leaves at two or three shoot tips and look closely. Clusters of small soft-bodied insects, or a sticky shine on the leaves below them, settles it.

  3. 3

    Leafhoppers, which curl the leaf edges as they feed

    This is the size and colour to look for after you tap a branch: pale green, wedge-shaped, and only a few millimetres long. They fly off the moment you get close, so you usually see them leaving rather than sitting still. Photo by Tyler Bishop via iNaturalist, CC BY
    Seen from directly above, the shape is the identification: a slim wedge, widest at the head and tapering to a point, in a pale green close to the leaf itself. Anything rounder, darker or larger than a grain of rice is something else. Photo by Tyler Bishop via iNaturalist, CC BY

    Leafhoppers curl the margins of a leaf rather than the whole blade, and they leave a fine pale speckling behind that a heat response does not. They are easy to miss because they leave the moment you get close.

    What to check first

    Tap a branch sharply over your open hand and watch. Quick-flying, tiny, pale green insects scattering off the plant is the confirmation, and it takes about ten seconds.

  4. 4

    Weed killer that drifted in from somewhere nearby

    This one is worth knowing about because nothing you do to the plant will help, and because it is the cause most often mistaken for a pest. The tell is the pattern: several unrelated plants affected at once, usually along the side of the garden facing a lawn or a road.

    What to check first

    Step back and look at which plants are affected and where they sit. Damage crossing several unrelated species at once, strongest on one side of the garden, points here rather than at anything living.

Still not sure

This is exactly what your county Extension office answers, for free. They are the local horticulture experts for your area, they know what is going around this season where you live, and they will look at a photo.

Find your local Extension office

Other plant problems

More than one of these is often happening at once. If the list above did not match what you are seeing, start from the symptom that fits best.

Sources

Keep the next one alive

Pollinator Patch gives you watering and seasonal care for the plants you already own, written for your region rather than for gardening in general.

Open on desktop
iPhone appAndroid app