Plant SOS · Symptoms
Why are my plant's leaves
curling? Causes and solutions
Curling leaves are an alarm signal — but a rather reassuring one. Unlike yellowing or rotting, leaf curling is often reversible within a few hours once the problem is corrected. The plant reacts to unfavorable environmental conditions by reducing its leaf surface to limit water loss or protect its tissues.
The key to diagnosis is the direction of the curl. Leaves curling upwards do not have the same cause as leaves curling downwards or inwards. This guide gives you the method to identify the cause in less than two minutes.
First step — the direction of the curl
The direction in which the leaves curl is the first diagnostic clue. Observe before acting.
⬆️ Upwards (edges rising)
The edges of the leaf rise upwards, forming a trough. A classic sign of lack of water, excessive heat, or dry air. The plant reduces its evaporation surface to conserve water.
⬇️ Downwards (edges dropping)
The edges of the leaf curve downwards. This can indicate overwatering, root stress, or a thrips infestation. Check the soil and the underside of the leaves.
"The direction of the curl
tells almost everything about the cause."
1. Lack of water — the most frequent cause
Cellular dehydration
When a plant lacks water, its cells lose turgor — the pressure that keeps tissues rigid and leaves wide open. The leaf curls upwards to reduce its surface and limit evaporation. This is a survival mechanism, not a disease.
2. Excessive heat or dry air
Thermal and hygrometric stress
Air that is too hot (above 28-30°C), a warm draft from a radiator, or a very dry atmosphere (humidity below 40%) causes the same curling reflex as drought. The plant loses water through its leaves faster than it can absorb it through its roots. This phenomenon is very common in winter with heating.
3. Overwatering
Asphyxiated roots
Paradoxically, too much water can also cause leaves to curl — but downwards this time. Roots asphyxiated by waterlogged substrate can no longer properly conduct water. The plant finds itself in a state of physiological drought despite moist soil. Downward curling can also be accompanied by yellowing and a musty smell.
4. Too much sun exposure
UV protection
Some plants — especially calatheas, marantas, and fittonias — curl their leaves in response to overly intense light exposure. This is a protective mechanism: by reducing the exposed surface, they limit damage from UV rays and overheating of the leaf blade.
5. Pests — mites or thrips
Sap-sucking infestation
Thrips and spider mites feed on leaf sap, which causes cellular imbalance and makes the leaf curl — often downwards or inwards. Curling due to pests is always accompanied by other visible signs: small dots, fine webbing, discolored or spotted leaves.
6. Natural reaction — some plants do this
Nyctinastic movement — normal!
Some plants naturally curl their leaves at night or in response to light variations. This is the case for calatheas, marantas, and some fittonias — a phenomenon called nyctinasty. If your plant's leaves curl in the evening and uncurl in the morning, this is completely normal and no action is needed.
💡 The specific case of calathea
The calathea is the queen of curling — it can curl for at least four different reasons: lack of water, overly dry air, too much direct sun, or natural nocturnal behavior. If your calathea is curling, start by checking the soil, then ambient humidity and light before panicking.
The Douceur Maison diagnosis
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🌿 To treat and prevent
Our recommended products
- 💦 Green Glass Mister — humidify foliage
- 💦 Premium 300ml Mister
- 🌿 Pokon Anti-Persistent Insect Spray 750ml — against mites & thrips
- 🥥 Coco Coir — draining ecological peat-free substrate for repotting
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Start diagnosis🌿 Guide written by the Douceur Maison Plant SOS team.
We write practical guides to help enthusiasts care for their indoor plants. · sosplantes@douceurmaison.fr
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