Why are my plant’s leaves curling?
Which way the leaf curls narrows it down: curling inward or downward usually means water stress, curling upward or cupping usually means light or heat.
The causes, and how to tell them apart
Underwatering most common
How to tell: Leaves curl inward or fold along the midrib, feel soft and limp, and the soil is dry.
What to do: Soak thoroughly and shorten the interval.
Heat or light stress common
How to tell: Leaves cup upward or curl away from a light source, often with faded or bleached patches, during hot or very bright weather.
What to do: Move to bright indirect light, out of hot afternoon sun.
Pests — mites, thrips or aphids check for this
How to tell: New growth is distorted and curled, with fine stippling, faint webbing in leaf axils, or sticky residue. Backlight the leaf against a window to see it.
What to do: Treat on a strict schedule — see the spider mite protocol. One spray does not clear an infestation.
Root problems less common
How to tell: Curling with wet soil, or a root ball so pot-bound that water runs straight through.
What to do: Check the roots and repot if they are circling the pot or rotting.
The species where curling is most often pests
Mites and thrips are the third cause above, and they are not evenly distributed — they ride dry, warm air and favour particular plants. These are the tracked species that list them among their usual pests, ordered by how much humidity they want, because the gap between that and your actual air is what invites the mites in.
| Species | Wants humidity | Prone to |
|---|---|---|
| Calathea | 55%+ | spider mites, thrips |
| Alocasia | 55%+ | spider mites, thrips |
| Boston fern | 55%+ | spider mites |
| Anthurium | 50%+ | spider mites, thrips |
| Areca palm | 50%+ | spider mites |
| Moth orchid | 50%+ | spider mites |
| Peace lily | 45%+ | spider mites |
| Croton | 45%+ | spider mites |
| Parlor palm | 45%+ | spider mites |
| Dieffenbachia | 45%+ | spider mites |
Check the underside of a curled leaf against a window before treating for anything else. Mite damage is stippled and fine; a watering problem is not.
By species
The likely answer differs by plant — these species have their own version of this problem:
Plantroster compares this month's photo against last month's, so slow changes — the ones you stop noticing because you see the plant every day — get flagged.
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General horticultural guidance, not a diagnosis of your specific plant.