Calathea leaves fold up at night and open in the morning. That is normal. Leaves that stay curled through the day are short of water at the leaf, and the reasons are thirst, dry air, hot sun, cold draughts, tap water, or roots damaged by wet soil. The direction and feel of the curl, and the soil, separate them.
What the curl tells you
| What you see | Most likely cause | Check this first |
|---|---|---|
| Leaves rolled inward lengthwise, limp, soil dry, pot light | Underwatering | Soil to the bottom; pot weight |
| Leaves curled at the edges with crisp brown margins, room dry or heated | Low humidity | Position near heaters; season |
| Leaves curled and faded or bleached on the window side | Too much direct light | Hours of direct sun |
| Leaves curled and edges browning after a change of water | Tap water | Water source |
| Curling with yellowing lower leaves, soil wet, sour smell | Overwatering and root damage | Root check |
| Sudden curling after a cold night or a draught | Cold | Where the plant sat |
| Curling with sticky residue or fine webbing under the leaves | Spider mites | Underside of leaves with a lens |
Underwatering
Calathea roots are fine and dry out quickly. A dry plant rolls its leaves inward into tubes, goes limp, and the soil is dry to the bottom and pulling from the pot. What to do: water thoroughly, rewet from below if the soil has shrunk, and afterwards water whenever the top of the soil is just dry, which in summer can be every few days. The leaves unroll within a day or two.
Low humidity
Calathea comes from humid forest floors and curls its leaf edges in a dry room, with crisp brown margins, especially in heated rooms in winter. What to do: move it away from heaters and vents, group it with other plants, stand it on a tray of wet pebbles, or run a humidifier. A bathroom or kitchen window with indirect light suits it. Misting is not a fix.
Too much direct light
Direct sun through glass curls and fades the leaves that face it, bleaching the pattern. What to do: move the plant back from the window or filter the light. Calathea wants bright indirect light and tolerates fairly low light.
Tap water
Calathea is sensitive to the minerals, chlorine and fluoride in some tap water, curling and browning at the edges after a change of water. What to do: water with rainwater, filtered or distilled water for a few weeks and compare the new leaves.
Overwatering and root damage
In soil that stays wet, the roots suffocate and the plant cannot supply its leaves even in a wet pot. The leaves curl, the lower ones yellow, and the soil smells sour. What to do: slide the plant out, trim brown mushy roots, repot in fresh airy mix, and water only when the top of the soil is dry.
Cold
Below about 15 degrees Celsius, or in a draught from a door or window, calathea curls its leaves suddenly. What to do: move it to a warm spot away from draughts. The leaves relax within a few days if the chill was brief.
Spider mites
Spider mites suck the leaves, which curl, speckle and dull, with fine webbing at the leaf joints and undersides. What to do: rinse the plant thoroughly under the shower, wipe the undersides, and repeat weekly for a month. Raising the humidity discourages them.
What to do today, by cause
- Underwatering: soak thoroughly, rewet from below if needed, water when the top is just dry.
- Low humidity: move from heaters, group plants or use a humidifier.
- Direct light: move back from the glass or filter the light.
- Tap water: switch to rainwater or filtered water.
- Overwatering: unpot, trim, repot in airy mix.
- Cold: move to a warm spot away from draughts.
- Spider mites: rinse and wipe weekly, raise humidity.
Frequently asked questions
Why do calathea leaves curl at night?
That is the plant's daily movement and is normal. Leaves that fold at dusk and open in the morning are healthy. Leaves that stay curled all day are the problem.
Will curled calathea leaves uncurl?
Leaves curled from thirst, cold or dry air uncurl within a few days of the fix. Leaves that have gone crisp at the edges do not recover but stop spreading, and new leaves come in flat.
Should I mist my calathea?
Misting wets the leaf briefly and does not change the room's humidity, and wet leaves in still air can spot. Group plants, use a pebble tray or a humidifier instead.
How often should I water a calathea?
Whenever the top of the soil is just dry, checked by finger, which is every few days in summer and weekly or less in winter. Do not let it dry to the bottom and do not leave it standing in water.