Boston Fern
Nephrolepis exaltata
also called nephrolepis
Arching fronds that brown off the moment the air dries; humidity does more for it here than anything you can feed it.
- Type
- Houseplant · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Sunlight
- Bright, indirect light — direct sun is too harsh for the fronds.
- Watering
- Keep the soil steadily moist, though never standing wet.
- Feeding
- A half-strength balanced feed once a month, spring through early autumn.
- Frost tolerant
- No
- Pruning
- Take dead and browned fronds off at the base as they appear.
- Mar–Dec Spring Growth
- Jan–Mar Spring Growth
- Plant spacing
- 23.6 in
- In-row spacing
- 23.6 in
- Between rows
- 2 ft 6 in
- Square-foot density
- Not suited to SFG
- Root system
- A creeping rhizome with wiry black roots
- Working depth
- 4–12 in
- Can reach
- 18 in down where the soil allows
- Spread
- 24 in–4 ft across, about 1–2× the width of the plant
- Shallowest pot
- 8 in of soil
The rhizome runs at the surface under leaf litter, which is exactly where a fern wants it: covered, damp and never disturbed. Bury it in soil and it rots, leave it bare and it dries, so leaf mould over the top is the whole of its cultivation.
The habit is Boston Fern’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- Cats and dogs
- Confirmed safe
We say a plant is safe only where a named poison-control reference names that exact species and records it as non-toxic to both cats and dogs. Most plants are on nobody’s list, and their absence here is not a judgement about them. This is a record of what those references say, not veterinary advice, and it cannot account for your own animal, the quantity eaten, or a plant treated with anything.
The ASPCA prints the cultivar and its own spelling of exaltata. We hold Nephrolepis exaltata. The same species.
- Mealybugs Mealybugs down at the frond bases
- Scale insects Scale insects under the fronds
- Root & crown rot Root rot where the pot is left waterlogged
- Brown frond tips from dry air, or from fluoride in tap water
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Hoverfly Syrphidae
Bee-mimicking flies whose legless larvae graze aphid colonies clean while the adults pollinate. A ribbon of shallow, nectar-rich flowers kept in bloom all season recruits wave after wave of them.
- Ladybird (lady beetle) Coccinellidae
The gardener’s favorite ally: adults and their alligator-shaped larvae each eat thousands of aphids, plus scale, mealybugs, and other soft-bodied sap-suckers. Grow flat, open flowers for the adults and never spray a colony that ladybird larvae are already working.
- Green lacewing Chrysoperla carneaHunts Mealybugs
Its bristly larvae — "aphid lions" — impale aphids, mealybugs, thrips, and mite colonies, eating hundreds a week. Adults feed on nectar and pollen from small open flowers and overwinter in hollow stems left standing.
Green-leaved houseplants, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com