Boston fern: brown crispy edges
Why are the leaf edges brown and crisp?
On boston fern, the likeliest cause is air too dry. Browning follows the leaf margin evenly all the way round, with a thin yellow band between brown and green.
- 1Air too dry
Ranked here because it wants 50% humidity as a floor, and heated indoor air in winter runs nearer 30%.
How to tell. Browning follows the leaf margin evenly all the way round, with a thin yellow band between brown and green. Worst in winter when heating is on.
What to do. Group plants together, or run a humidifier nearby. Misting raises humidity for about ten minutes and is not a fix.
- 2Watering too little, or too erratically
Ranked here because at a 3–6 day interval there is little margin before it dries out completely.
How to tell. The pot is light, the soil has shrunk from the sides, and the browning is worst on the leaves furthest from the stem.
What to do. Water thoroughly rather than often. A small splash wets the top inch and never reaches the roots doing the work.
- 3Too much direct sun
How to tell. Browning on the leaves nearest the glass, and on the sun-facing half of individual leaves, rather than uniformly round the margin.
What to do. Move it back from the window or filter the light. Scorched tissue does not recover; you are protecting new growth.
- 4Minerals in tap water
How to tell. Tips brown first and the edge follows, on a plant that is otherwise healthy and correctly watered. A white crust on the soil surface or pot rim confirms it.
What to do. Switch to filtered or rainwater, or leave tap water standing overnight. Flush the pot thoroughly every few months to wash salts out.
- 5Fertiliser salts
How to tell. Brown tips plus a visible white crust on the soil or pot rim, on a plant fed more than monthly.
What to do. Flush the pot with several pot-volumes of water and feed at half strength, at most monthly in growth.
Why that order, for this plant
The ranking above is not a generic list. It is computed from this species' own record — a watering interval of 3–6 days, a tropical understory origin, a humidity floor of 50%, and a light range from low to bright-indirect. Change those figures and the order changes with them.
That is the whole point of a per-species page. Brown crispy edges on a plant watered every three days and brown crispy edges on one watered every three weeks almost never have the same cause, and a list that ranks them identically is worth nothing to either owner. You can check the reasoning against the care fields on the species entry, which is where these numbers come from.
No percentages appear on this page. We have not run a grower survey, and a confident-sounding figure with no dataset behind it is worse than none. Order and distinguishing tests are what we can honestly give.
What Missouri Botanical Garden records
An independent authority on this species' problems, for comparison with the ladder above.
Scale, mealybugs, slugs and white fly may appear. Indoor leaf drop can be bothersome.
Missouri Botanical Garden Plant Finder — Nephrolepis exaltata. Checked 2026-09-11.
Other problems recorded for this species
- Frond drop this week
- Yellow leaves this week
Also for this species
Full care entry with light, watering and soil. How to propagate it. Toxicity to cats and to dogs.
Sources
- Missouri Botanical Garden Plant Finder — Nephrolepis exaltata Pest and disease record. Checked 2026-09-11.
- Royal Botanic Gardens Kew, Plants of the World Online — Nephrolepis exaltata Accepted name and family. Checked 2026-09-11.
- ASPCA Animal Poison Control — Nephrolepis exalta bostoniensis Relevant if a damaged plant is being chewed rather than merely ailing.
- This database's own care record for Nephrolepis exaltata — the watering, humidity and light figures the ranking is derived from.
Compiled and edited by Tony Valcarcel · 2026-09-12
Cause ordering is derived from this species' recorded care requirements, and the
derivation is stated above so you can disagree with it. It is not a diagnosis, and
a plant can have two problems at once. How this is sourced.