Why Are My Arrowroot Leaves Curling?

Low humidity

Low humidity is the primary cause of leaf curling and tip browning in arrowroot. As a Marantaceae plant adapted to the humid rainforest understory, arrowroot needs relative humidity above 50 to 60%. In UK homes in winter, central heating drops humidity to 30 to 40%, causing the leaf margins and tips to curl and turn brown. The curling caused by low humidity is persistent and does not resolve with watering alone.

Fluoride and chlorine in tap water also cause tip browning in Marantaceae plants. Watering with rainwater or leaving tap water to stand overnight in an open container before use reduces the impact of these dissolved chemicals.

What to do

• Stand the pot on a gravel tray with water. Mist with lukewarm rainwater or settled tap water every morning. Group with other humidity-loving plants. Move away from radiators. Use a humidifier if other methods are insufficient.
• Switch to rainwater or settled tap water to reduce fluoride and chlorine damage.

Drought and overwatering

Arrowroot needs consistently moist compost during the growing season. If the compost dries out completely the leaves curl and the whole plant droops; recovery is usually rapid once the plant is watered thoroughly. Overwatering causes root rot: the rhizomes and roots rot in persistently wet compost, producing yellowing lower leaves, soft stem bases, and eventually wilting despite wet compost.

What to do

• Water when the top centimetre of compost is dry. Do not allow the plant to sit in water. Use a pot with drainage holes and a free-draining compost. Reduce watering in winter when growth is slow. If root rot is suspected, remove the plant from its pot, cut away soft, brown roots and rhizome sections, and repot in fresh compost.

Direct sunlight

Arrowroot is a shade-adapted plant and does not tolerate direct, intense sunlight. A south-facing windowsill in summer will cause the leaves to curl, fade, and develop scorched brown patches at the edges. The ideal position is bright indirect light: near a north or east-facing window, or a few metres from a south or west-facing window with a thin curtain to diffuse the light.

What to do

• Move the plant away from direct sunlight. Bright indirect light is ideal. Outdoors in summer, position in dappled shade under a tree or pergola rather than in full sun.

Cold and draughts

Arrowroot is damaged by temperatures below 15°C and shows immediate distress from cold draughts. The leaves curl and turn yellow-brown at the tips and margins when the plant is exposed to cold air from a window, door, or air conditioning. Cold, damp compost in winter (from overwatering combined with low temperatures) accelerates root rot.

What to do

• Keep arrowroot at a minimum of 15°C at all times. Move away from cold windows in autumn. Keep away from air conditioning vents. Reduce watering significantly in winter to match the plant's reduced water uptake.

Frequently asked questions

Why are my arrowroot leaves curling?

Arrowroot (Maranta arundinacea) leaves curl most commonly because of low humidity, drought, cold draughts, or direct sunlight. Arrowroot is a tropical plant in the Marantaceae family, closely related to prayer plants and calatheas. Like its relatives, it is adapted to the shaded, humid rainforest floor and communicates distress by curling and browning its broad, oval leaves when humidity falls, water is insufficient, temperatures drop below 15°C, or light is too intense. Low humidity is the most common cause in UK homes: the leaf margins and tips curl and brown when relative humidity is below 50%, particularly in winter with central heating. Drought causes the whole leaf to curl inward and the plant to droop. Direct sunlight scorches the leaves and causes curling at the burned edges.

How do I grow arrowroot as a houseplant in the UK?

Arrowroot (Maranta arundinacea) can be grown as a container plant in the UK in a warm, bright but indirect light position indoors or in a heated greenhouse. It prefers temperatures above 16°C and high humidity. Plant rhizomes (or divisions from an existing plant) in a well-draining, moisture-retentive compost in a pot with drainage holes. Water regularly during the growing season, keeping the compost consistently moist but never waterlogged. Feed every two weeks from spring to summer with a balanced liquid fertiliser. Stand on a gravel tray with water to maintain humidity, or mist regularly. Arrowroot grows to 60 to 90 centimetres tall and produces distinctive green and white patterned leaves similar to those of prayer plants. Like prayer plants and calatheas, arrowroot exhibits nyctinasty: the leaves fold upward in the evening and reopen in the morning. It can be placed outside on a warm, sheltered patio in summer but must be brought indoors well before the first frost.

What is arrowroot and how is it different from a prayer plant?

Arrowroot (Maranta arundinacea) and prayer plants (Maranta leuconeura and related species) are closely related plants in the same genus (Maranta) and family (Marantaceae). The key difference is their primary use: Maranta arundinacea is grown primarily for its starchy rhizomes, which are ground to produce arrowroot powder, a fine, easily digested starch used in cooking and baking. Maranta leuconeura (the prayer plant) is grown purely as an ornamental houseplant for its dramatically patterned leaves. The plants have similar foliage and cultural requirements. Calatheas (now reclassified into several genera including Goeppertia) are close relatives in the same family, often called by gardeners the 'calathea family', and share the same care needs: high humidity, indirect light, moist but well-drained compost, and warmth.

Why are the tips of my arrowroot leaves turning brown?

Brown tips on arrowroot leaves are caused by low humidity, fluoride or chlorine in tap water, drought, or cold draughts. Low humidity is the most common cause in UK homes: the leaf tips are the most vulnerable part of the leaf and dry out first when the surrounding air is too dry. Fluoride and chlorine in tap water are known causes of tip browning in Marantaceae plants; watering with rainwater or distilled water, or leaving tap water to stand overnight before using it, reduces this. Drought causes tip browning that extends down the leaf margins. Cold draughts (from a nearby window or door) cause rapid tip browning and curling. Trim brown tips with sharp scissors angled to follow the natural leaf shape. Addressing the underlying humidity and watering issues prevents further browning.