Calathea has a reputation for being difficult, and in UK homes specifically, that reputation is earned. British tap water, central heating, and the low winter light levels that most UK rooms experience combine to create conditions that challenge calathea at almost every point in its biology.
This guide doesn’t pretend otherwise. But it does explain why calathea is difficult — and that understanding changes the care entirely. Most calathea deaths in UK homes come from two specific, fixable problems: the wrong water, and not enough humidity. Address both, and the plant becomes significantly more manageable.
What Calathea Is
Calathea (which now encompasses many plants reclassified under Goeppertia in recent taxonomy, though the common name persists) is a genus of tropical plants native to the rainforest floors of Central and South America. They evolved under a dense canopy with filtered light, consistent warmth, high humidity, and naturally soft rainwater.
UK conditions offer almost none of this by default. The water is hard in most of England and Wales. The air is dry in centrally heated homes. Winter light is low. This is not a plant that will forgive being treated like a pothos.
The reward for getting it right is genuine: the leaf patterning on calatheas — stripes, feathering, deep purples, silver overlays — is some of the most extraordinary in the houseplant world. And the nyctinastic movement, the way the leaves fold upright at night and open again in the morning, is one of the more genuinely surprising things a houseplant can do.
The Water Problem
This is the most important section in this guide for UK owners.
Calathea is acutely sensitive to fluoride, chlorine, and dissolved minerals in tap water.1 UK mains water is treated with fluoride in many areas and chlorine universally. In most of England (and parts of Wales), tap water is also hard — high in dissolved calcium and magnesium carbonates. For calathea, regular watering with UK tap water causes the minerals to accumulate in the leaf tissue, producing the characteristic brown edges and crispy tips that make owners assume the plant is too dry or too cold. It is neither — it is being slowly poisoned by water chemistry.
The fix is simple but non-negotiable: use a different water source.
Options in order of preference:
- Collected rainwater: The best option. Naturally soft, free of fluoride and chlorine, close to calathea’s natural water source. If you have outdoor space, a water butt is a worthwhile investment if you keep calatheas.
- Filtered water: A jug filter (Brita-type) removes chlorine and significantly reduces mineral hardness. Not perfect, but a substantial improvement over direct tap water.
- Tap water left to stand overnight: Allows chlorine to off-gas, but does not remove fluoride or calcium. A partial improvement — useful if rainwater or filtering is not practical, but not a complete solution in hard water areas.
This single change — switching water source — resolves the majority of calathea brown edge problems in UK homes. It is not optional for long-term success with this plant.
Light
Calathea needs bright to medium indirect light, but absolutely no direct sun. The large, patterned leaves are photosynthetically efficient and adapted to dappled forest-floor conditions — direct sunlight bleaches the leaf patterns, damages the tissue, and causes the very brown patches it’s so easy to attribute to other causes.
A north- or east-facing room is well-suited to calathea’s light requirements — moderate, consistent indirect light with no harsh direct sun exposure. South- and west-facing rooms work well if the plant is positioned away from the direct sun path, diffused behind a sheer curtain, or placed several metres back from the window.
UK winter light: Calathea can struggle in very dark UK winter conditions. If placed in a north-facing room with little natural light, growth essentially stops and the plant becomes more susceptible to root issues from slow soil drying. In genuinely dark spaces, a grow light on a timer (twelve hours per day at 2,500–5,000 lux) provides the minimum needed to maintain health through winter.
Humidity
Calathea needs 60% humidity or above for optimal health — well above what most UK homes provide. Centrally heated UK homes in winter often drop to 30–40% humidity. At low humidity, the leaf edges brown, new leaves emerge unfurling with brown edges already forming, and the plant looks perpetually stressed regardless of other care.
Effective solutions:
Humidifier: The only fully reliable solution for calathea. A small ultrasonic humidifier placed near the plant (not directly blowing on it) and set to maintain 60% or above transforms calathea care. If you intend to keep calatheas long-term in a UK home, this is the single best investment you can make.
Pebble tray: Helpful, but limited. A large, shallow tray of wet pebbles under the pot raises local humidity by a few percentage points — better than nothing, but not sufficient to compensate for very dry central heating air on its own.
Grouping: Placing calathea among other plants improves local humidity through collective transpiration. Combining this with a pebble tray and keeping the group away from radiators is a reasonable approach if a humidifier isn’t practical.
Misting: Not recommended. Misting wets the leaf surface, which can encourage fungal issues (particularly in cooler UK conditions with limited airflow). It also provides only momentary humidity relief. The time spent misting is better invested in a consistent pebble tray setup.
Watering
Water calathea with soft or filtered water (see above) when the top inch of soil is dry. It prefers consistent moisture — not soggy, but never fully dried out. Unlike drought-tolerant plants, calathea’s fine root structure does not hold water reserves well, and drying out completely damages the root hairs and causes stress visible in the leaves.
In summer, this is typically every five to seven days. In winter, ten to fourteen days. Always check the soil rather than following a fixed schedule — UK winter conditions mean soil dries much more slowly than in summer.
Do not leave calathea sitting in water — empty the saucer after twenty minutes. Wet feet in cool temperatures are a reliable route to root rot.
Temperature
Calathea prefers 18–27°C and is damaged by cold. Keep away from cold draughts — calathea near a draughty sash window in winter will show cold damage (dark, water-soaked patches on the leaves) quickly. Do not place in an unheated room or conservatory through winter.
Temperature fluctuations stress calathea more than most houseplants. A consistent, draught-free position at normal room temperature is what it needs.
Soil and Repotting
Use a well-draining, moisture-retentive mix: peat-free multipurpose compost with added perlite (around 20%) is suitable. The soil should hold some moisture but drain well enough that it doesn’t stay wet for days after watering.
Calathea doesn’t need frequent repotting and tends to be slightly sensitive to the disturbance. Repot in spring only when clearly pot-bound — when roots are circling the base of the pot or the plant is drying out very rapidly after watering. Move up only one pot size.
The Prayer Plant Movement
The leaf movement — technically called nyctinasty — is driven by changes in water pressure in specialised cells at the base of each leaf stem (the pulvinus). As light fades, these cells change their water pressure balance, causing the leaf to fold upward. In the morning, they refill and the leaf opens flat again.2
If your calathea’s leaves have stopped moving, the most common causes are: insufficient light (the movement is driven by the light-dark cycle), very dry air reducing the water pressure in the pulvinus, or root stress. A calathea that moves consistently is, in my experience, the single most reliable sign the plant is in genuinely good health.
Common Problems
Brown leaf edges: Almost always hard water or fluoride accumulation, or low humidity. Switch to rainwater or filtered water, and increase humidity. This is the defining UK problem with calathea.
Yellowing leaves: Overwatering is most likely. Reduce watering frequency and check for root rot.
Pale or bleached leaves: Too much light, or direct sun. Move further from the light source.
Leaves rolling or curling: The plant is too dry or too cold. Check soil moisture and temperature; move away from draughts.
Leaves not moving: Insufficient light contrast between day and night, or the plant is too stressed by other conditions to maintain the nyctinastic response. Address the most obvious care issue first.
New leaves emerging with brown edges already: Low humidity — the leaf is forming in dry air before it’s even fully open. This requires a humidifier to properly fix.
Footnotes
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Royal Horticultural Society (2024). ‘Calathea’. Available at rhs.org.uk/plants/calathea/growing-guide. The RHS specifically notes fluoride sensitivity in Calathea (and Goeppertia) species and recommends soft water or rainwater, citing leaf tip browning as the primary symptom of fluoride accumulation in hard water areas. ↩
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Antkowiak, B. & Engelmann, W. (1995). ‘Oscillations of apoplasmic K⁺ and H⁺ activities in pulvini of Desmodium motorium’. Journal of Experimental Botany, 46(6), pp. 847–856. The biochemical mechanism of nyctinasty — potassium ion flux between flexor and extensor cells in the pulvinus — is established across the Marantaceae family to which Calathea/Goeppertia belongs. The movement is light-entrained and dependent on healthy, hydrated pulvinus cells. ↩
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