Why Are My Calathea Leaves Curling?

Low humidity

Calatheas originate from the tropical rainforest floor, where humidity rarely dips below 60 percent. In a typical UK home, especially in winter when central heating is running, indoor humidity can fall to 30 to 40 percent. The plant responds by curling its leaves inward to reduce the surface area losing moisture through transpiration. This is the single most common reason calathea leaves curl.

The tell is that leaves curl even when the compost is still moist. Pick up the pot and if it feels appropriately heavy, humidity rather than water is the problem. Leaves may also feel slightly crisp or develop brown edges at the same time.

What to do

• Stand the pot on a wide tray filled with pebbles and water, keeping the base of the pot above the waterline so roots are not sitting in it.
• Run a cool-mist humidifier nearby, or group several houseplants together to create a localised humid microclimate.
• Move the plant away from radiators, heating vents, and draughty windows.
• Avoid misting directly onto leaves as it provides only brief relief and can create conditions for fungal leaf spot.

Underwatering

If the compost has dried out too much between waterings, the plant pulls water from its leaf cells, causing them to lose turgor and curl inward. Unlike humidity-related curling, this is accompanied by lightweight compost that may have pulled away from the sides of the pot when very dry.

Push a finger about 2 cm into the compost. Calatheas like to be watered when the top centimetre or two has dried out but well before the compost becomes completely dry. They should not be left bone dry for more than a day or two.

What to do

• Water thoroughly until it drains freely from the bottom, then empty the saucer after 30 minutes.
• If the compost has dried and shrunk away from the pot sides, bottom-water: place the pot in a bowl of room-temperature water for 20 to 30 minutes to allow the root zone to rehydrate from below.
• Establish a regular watering routine, checking the compost every few days in warm weather and weekly in winter.

Tap water sensitivity

Calatheas are more sensitive to water quality than almost any other common houseplant. Fluoride, chlorine, and mineral salts found in hard tap water accumulate in the leaf tissue over time and cause tip burn, browning, and curling. The damage typically starts at the tips and edges before spreading inward.

If your tap water is hard and you have been using it for several months, water quality is a likely contributor even when watering frequency is otherwise correct.

What to do

• Switch to rainwater collected in a water butt, or filter tap water through a jug filter.
• If tap water is all that is available, fill a jug the night before and leave it uncovered overnight to allow chlorine to off-gas.
• Repot into fresh compost annually to flush accumulated mineral salts from the root zone.
• Already damaged leaves will not recover fully, but new growth produced under improved water conditions should emerge clean and healthy.

Cold draughts

Calatheas dislike cold air movement. A position near a door that opens to the outside, a leaky window frame, or directly below an air conditioning unit exposes them to cold draughts that cause leaves to curl and develop pale or translucent patches. The damage is often more pronounced on the side of the plant closest to the cold air source.

Calatheas prefer temperatures between 18 and 24 degrees Celsius and should not be exposed to anything below 15 degrees. Even brief exposure to cold draughts can cause lasting damage to the patterned foliage.

What to do

• Relocate the plant to a stable, draught-free position away from exterior doors and windows that let in cold air.
• Keep calatheas away from air conditioning units, which simultaneously lower temperature and reduce humidity.
• During winter, move plants sitting on windowsills inward overnight so they are not caught between cold glass and warm room air.

Too much direct sunlight

As a forest floor plant, calathea is adapted to bright, filtered light rather than direct sun. Placed in a south or west-facing window that receives several hours of direct afternoon sun, the leaves curl to limit the exposed surface area and can bleach, scorch, or develop washed-out patches between the markings. Curling combined with faded colouring or crispy brown patches points to too much direct light.

What to do

• Move the plant to a position with bright indirect light: a metre or two back from a sunny window, or in a north or east-facing room.
• Filter direct sunlight through a sheer curtain or adjustable blind during the hottest part of the day.
• Scorched or bleached leaves will not recover their colour. Cut them off at the base so the plant can redirect energy into new healthy growth.

Frequently asked questions

Why are my calathea leaves curling inward?

Inward curling is almost always a sign of stress from low humidity or underwatering. Calatheas need humidity above 50 percent and consistently moist (not soggy) compost. Tap water with high fluoride or chlorine content can also cause curling and tip burn over time.

Should I mist my calathea to stop leaves curling?

Misting gives only brief relief and can encourage fungal leaf spots. A pebble tray filled with water, a room humidifier, or grouping several plants together provides more sustained humidity than misting.

Can I use tap water on calathea?

Many tap supplies contain fluoride and chlorine at levels that cause calathea tip burn and leaf curling over time. Using rainwater, filtered water, or leaving tap water to stand overnight before watering reduces this problem significantly.

Will curled calathea leaves uncurl?

Yes. If the cause is moisture or humidity stress, the leaves often uncurl within hours of watering or moving the plant to a more humid spot. Leaves damaged by cold or fluoride may not fully recover, but new healthy growth will appear once conditions improve.