Why do my houseplant leaves have brown crispy tips?

Brown, dry tips are a water-balance problem in the broadest sense: the leaf edges are the furthest point from the roots, so they are the first tissue to be sacrificed when water delivery falls short of demand. Several different causes produce the same symptom, which is why a single remedy so often fails.

Underwatering is the most obvious. If the compost dries out completely between waterings, or you water little and often so only the top layer ever gets wet, the tips go first. Water thoroughly until it runs from the drainage holes, then let the top few centimetres dry before repeating.

Low humidity is the classic cause in heated rooms during winter. Plants from tropical understoreys — calatheas, ferns, marantas — are the most sensitive. Grouping plants together, standing pots on a tray of damp pebbles, or moving them to a bathroom all help. Misting provides only brief relief.

Mineral build-up is widely underestimated. Salts from tap water and fertiliser accumulate in the compost and concentrate at the leaf margins, burning them. Flush the pot through with plenty of water every few months, feed at half strength, and consider rainwater or filtered water for sensitive species.

Root damage from overwatering produces identical symptoms, because rotted roots cannot take up water however wet the pot is. If the compost is constantly soggy and the plant is still browning, check the roots — healthy ones are firm and pale, not brown and mushy.

Less commonly, cold draughts or proximity to a radiator will do it. Trim damaged tips with scissors following the leaf's natural outline; they will not recover, but new growth should come clean.