Brown crisp edges on the leaves
Dry air, salt build up or a pot that dried out too far. How to tell the three apart, and why the brown part never turns green again.
What it usually is
1 Dry air
| How to tell | Thin, even browning right along the edge of several leaves, worst on the plants that come from forest floors: calatheas, marantas, ferns, alocasias. It gets worse in winter when the heating is on and better in a bathroom. |
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| The fix | Group plants together, stand them on a wide tray of damp pebbles with the pot on the stones rather than in the water, or run a small humidifier in that room. Misting raises the humidity for about ten minutes and is not a fix on its own. |
2 Salts from tap water and feed
| How to tell | Brown edges with a white or pale crust on the surface of the compost or around the drainage hole, on a plant that is watered little and often and fed regularly. |
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| The fix | Flush the pot: water slowly with three or four times its volume until it runs freely from the bottom, and empty the saucer. Do that every few months, feed at the strength on the bottle rather than above it, and use rainwater or water left standing overnight for the fussy species. |
3 The compost dried out completely
| How to tell | Browning that appeared after a fortnight away, often with a leaf or two lost entirely, and compost that has shrunk away from the side of the pot. |
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| The fix | Rehydrate slowly. Stand the pot in a bowl of water for twenty minutes so the compost swells back against the sides, then drain it thoroughly. A pot that has dried to that point sheds water straight down the gap otherwise. |
Through the year. Almost always worse from the first week the heating goes on until it goes off again. A plant that browns from November to March and stops in spring has an air problem, not a watering one.
A brown edge is dead tissue and it will not come back. That is worth saying first, because people spend weeks watching an old mark hoping it will heal. The question is never whether the brown goes away; it is whether the next leaf comes out clean.
Three things cause it and they are easy to tell apart once you know what to look at.
Dry air browns the outermost rim of the leaf, thinly and evenly, on the species that evolved under a canopy where the air never dries. It arrives with the heating and eases in spring. If your calathea browns every winter in the same spot and recovers each summer, you have your answer and no amount of careful watering will change it.
Salt browns the edge more raggedly and comes with evidence: a pale crust on the compost, a rim around the drainage hole, sometimes a chalky film on a terracotta pot. Every watering leaves behind a little of what was dissolved in it, and feeding adds more. Watering little and often is what concentrates it, because the water evaporates from the surface and leaves the salts behind rather than carrying them out of the bottom. The cure is to flush the pot properly two or three times a year.
A pot that dried right out browns whole sections rather than a rim, and usually costs a leaf or two. The tell is the compost pulling away from the side of the pot. Water poured onto that runs straight down the gap and out of the bottom, so the plant stays dry while you believe you have watered it. Standing the pot in water for twenty minutes is the only reliable way back.
What to do about the marks themselves: if you want to tidy a leaf, cut just inside the brown following the leaf’s own shape, and leave a hairline of brown rather than cutting into green, which only makes a new brown edge. Or leave them. A leaf that is three quarters green is still paying its way, and the plant will retire it in its own time.
Entries that name it
What the journal says about this symptom on each plant.
| Aloe vera | Sudden full sun after a spell indoors, or cold draught. Introduce strong sun over two weeks rather than in one afternoon, and keep it away from a window that is opened in winter. |
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| Areca palm | Direct sun through glass, or air blowing from a heater. Move it out of the sun beam and away from any vent or radiator. |
| Bird of paradise | Dry air indoors, or salts from feeding. Water more evenly, flush the pot with plain water every couple of months, and keep it away from radiators. |
| Blackberry | Drought stress while the fruit is swelling, which also produces small, dry, poorly flavoured berries alongside the leaf scorch. Water deeply during any dry spell that coincides with fruiting, rather than assuming an established plant needs nothing at all. This is the one point in the season it genuinely benefits from attention. |
| Boston fern | Dry air, which is the fern's whole difficulty indoors. Move it to a bathroom or kitchen, stand it on a tray of wet pebbles, and keep it away from radiators and air conditioning. |
| Calathea | Dry air, hard or chlorinated water, or too much feed. Switch to rainwater, raise the humidity around the plant, and halve the feed. Trim the brown off with scissors following the leaf shape. |
| Chinese money plant | Direct sun through glass, or very dry air beside a radiator. Move it out of the sun beam and away from the heat source. |
| Coriander | The compost dried out. Water more evenly and mulch the surface. A single dry spell is enough to start it flowering. |
| Croton | Dry air, or a pot that dried out completely. Water more evenly, raise the humidity around the plant, and keep it away from radiators. |
| Dumb cane | Dry air, or a pot that dried out completely. Water more evenly, group it with other plants, and keep it away from radiators. |
| English ivy | Dry heat, especially near a radiator. Move it to a cooler brighter place, water more evenly, and raise the humidity around it. |
| Fiddle-leaf fig | Dry air, underwatering, or direct sun through glass. Water more evenly, move it out of the sun beam, and keep it away from radiators and air conditioning. |
| Heartleaf philodendron | Dry air or a pot that dried out completely. Water more evenly, move it away from radiators, and group it with other plants to lift the humidity around it. |
| Inch plant | Dry air, or a pot that dried out. Water more evenly and keep it away from radiators. Cut the worst stems back and let it regrow. |
| Mint | The compost dried out. Keep it damp. Stand a pot in a saucer of water in high summer, which is the one plant here where that is good advice. |
| New Zealand broadleaf | Cold, drying wind scorching the leaf edges, especially on a young plant in an exposed spot before it has toughened up. Shelter a new hedge from the worst of the prevailing wind for its first year or two, with a temporary windbreak if the site is very exposed. An established hedge is one of the more wind-tolerant choices available and stops needing this protection. |
| Parlour palm | Direct sun through glass, or a radiator nearby. Move it out of the sun beam and away from the heat. |
| Photinia | A late spring frost catching the soft red new growth, or cold drying wind on an exposed site. Grow it against a south- or west-facing wall in a frost-prone garden, and hold off on the last trim of the season early enough that new growth has time to harden before the cold. |
| Prayer plant | Dry air, or minerals and chlorine in tap water. Switch to rainwater or filtered water, raise the humidity around the plant, and keep it away from radiators. |
| Rubber plant | Dry air, underwatering, or salt built up from feeding. Water more evenly, move it away from radiators, and flush the pot with plain water every few months to wash out salts. |
| Swiss cheese plant | Low humidity or a long dry spell. Water more evenly and move it away from heaters and air conditioning. Group it with other plants. |
| ZZ plant | Direct sun through glass, or a very dry hot spot beside a radiator. Move it out of the sun beam and away from the heat. Damaged leaflets do not recover, so cut the worst stems out at the base. |
Questions from the margin
- Why do my plant's leaves have brown crispy edges?
- Three things cause it. Dry air browns the outermost rim evenly, and gets worse the week the heating goes on. Salts from tap water and feed brown it more raggedly and leave a pale crust on the compost. And a pot that dried out completely browns whole sections at once.
- Should I cut the brown edges off?
- Only if you want to. The brown is dead and will not spread or heal. If you do trim, cut just inside the brown following the leaf's own shape and leave a hairline of brown, because cutting into green tissue simply makes a new brown edge.
Checked against RHS, Houseplants: brown leaf tips and edges; Clemson Cooperative Extension, Indoor plant problems.