Boston ferns are lush and forgiving outdoors in summer, then often turn brown and shed all over the floor once they come inside. The reason is simple: most homes are drier and dimmer than a shady porch. Boston fern care indoors comes down to three things: bright but indirect light, soil that never dries out completely (but is not soggy), and as much humidity as you can give it. This guide covers everyday indoor care, how to bring a fern in for winter, and what to do when it turns brown.
Boston Fern Care Snapshot
| Factor | Ideal indoors | Avoid |
|---|---|---|
| Light | Bright, indirect light | Hot direct sun through a south window; very dark corners |
| Temperature | About 60 to 70 °F | Frost; heat vents and drafts |
| Water | Moist soil that never dries out completely; less in winter | Bone-dry soil; waterlogged soil |
| Humidity | High: pebble tray, kitchen or bathroom | Dry, heated air |
| Feeding | Light feeding in the growing season | Fertilizing in winter |
| Pets | Non-toxic to cats, dogs and horses |
Sources: NC State Extension Plant Toolbox (Nephrolepis exaltata); N.C. Cooperative Extension, Greene County (2021); ASPCA.
Light and Temperature
The Boston fern (Nephrolepis exaltata), native to tropical and subtropical America according to NC State, grows naturally in filtered light. NC State recommends bright, indirect light and warmth of 60 to 70 °F. Indoors, that means near an east or north window, or a few feet back from a brighter window. The N.C. Cooperative Extension Greene County center says ferns need moderate, indirect light and should be kept away from south-facing windows, where harsh light can burn the frond edges.
Keep it away from heating vents, radiators and cold drafts. Too little light gives thin, pale, stretched fronds; too much direct sun gives scorched, bleached edges.
Watering a Boston Fern Indoors
NC State says Boston ferns need moist soil that should never be allowed to dry out. In practice, check the soil every few days and water when the surface just starts to feel dry, soaking the pot until water runs out of the drainage holes. Empty the saucer so the pot does not stand in water.
- Hanging baskets dry out fastest. Take them down and water in a sink, or soak them from below; see our bottom watering guide.
- In winter, water less. NC State notes that overwatering a dormant fern can lead to root rot.
- Plastic or glazed pots hold moisture longer than terracotta, which suits a fern.
Humidity
NC State is direct: this fern needs high humidity. It suggests placing it near kitchens and bathrooms, or on a tray of wet pebbles. The Greene County article also recommends setting the pot on a plate of gravel with water. Grouping plants together helps a little, and a room humidifier helps most in winter, when heating dries the air. Keep the pot sitting on the pebbles, above the water line, not in it.
Dry air is the number one reason indoor Boston ferns brown. If your home is very dry, a bright bathroom is often the best spot in the house.
Soil, Feeding and Repotting
Use a quality, moisture-retentive potting mix in a pot with drainage holes. Feed lightly with a balanced houseplant fertilizer during spring and summer, following the label; ferns are light feeders and too much fertilizer builds up salts that brown the fronds (see our white crust guide). Stop feeding in fall and winter. The Greene County article says not to fertilize overwintering ferns at all. Repot or divide in spring when the fern fills its pot.
The brown dots on the undersides of mature fronds are normal. NC State explains they are spores, not pests or disease.
Boston Fern Care Indoors in Winter
If your fern spent summer outdoors, bring it in before frost. The Greene County article notes ferns tolerate cool weather but do not like frost and definitely not a hard freeze. Its steps:
- Clean it first. On a warm day (60 °F or more), thoroughly soak the fern, spray the undersides of the fronds and the canopy to dislodge insects and loose leaves, and let it dry completely before bringing it in.
- Trim lightly. There is no need for a hard prune unless space is tight; just remove stragglers and shape it.
- Choose a cool spot with moderate, indirect light, away from south windows.
- Water minimally, only once the soil is dry, and do not fertilize at all, since the fern is not actively growing.
- Expect some change. Paler color and occasional dropped leaves are normal. If leaves drop heavily, move the fern to a cooler spot and add a gravel-and-water tray for humidity.
If you have nowhere bright, there is a dormant option. An Ask Extension expert notes Boston fern won’t survive temperatures below 30 °F, and suggests storing it in a cool place such as a basement or garage, where it stays dormant and needs water only about once a month. It will look rough by spring, but it can regrow when it goes back outside.
Why Is My Boston Fern Turning Brown?
| What you see | Likely cause | Fix |
|---|---|---|
| Brown, crispy tips and fronds | Dry air | Pebble tray, humidifier, or move to a bright bathroom or kitchen |
| Whole fronds brown and dry, soil pulling from the pot | Soil dried out | Soak thoroughly, then water before it dries completely |
| Brown and yellow fronds, soggy soil, mushy base | Overwatering, root rot (especially in winter) | Let the surface dry a little; water less in winter |
| Brown underneath, inside the plant | Old inner fronds dying back, often from low light | Remove dead fronds at the base; more indirect light |
| Scorched, bleached edges | Direct sun | Move away from a south window |
| Brown tips with white crust on soil | Fertilizer salts | Flush the pot with plain water; feed less |
| Leaflets dropping after coming indoors | Adjusting to lower light and drier air | Normal in small amounts; cooler spot plus humidity if heavy |
Sources: NC State Extension; N.C. Cooperative Extension Greene County; Ask Extension.
Snip fully brown fronds off at the base with clean scissors; they will not turn green again. New fronds grow from the center once conditions improve.
Pests
NC State notes that scale or spider mites can be a problem when the air around the plant is too dry. Raising humidity helps prevent both. Check frond undersides when you water: scale looks like small brown bumps, spider mites cause fine speckling and webbing. See our guides to spider mites and scale. Don’t confuse the neat rows of spores under mature fronds with pests.
Is Boston Fern Safe for Cats and Dogs?
Yes: non-toxic
The ASPCA lists Boston fern (Nephrolepis exaltata bostoniensis) as non-toxic, and NC State tags it non-toxic for cats, dogs and horses. It is one of the safest leafy houseplants for pet households. See more in our cat-safe plants list.
Love ferns? Our maidenhair fern care guide and staghorn fern care guide cover two other popular indoor ferns.
Frequently Asked Questions
How do you take care of a Boston fern indoors?
Give it bright, indirect light, temperatures around 60 to 70 °F, soil that never dries out completely and high humidity, as NC State Extension recommends. A pebble tray or a spot in a bright bathroom or kitchen helps.
How often should I water a Boston fern indoors?
Whenever the soil surface starts to feel dry, which may be every few days in a warm room. NC State says the soil should never be allowed to dry out. Water less in winter to avoid root rot.
Why is my Boston fern turning brown and crispy?
Almost always dry air or dry soil. Raise the humidity with a pebble tray or humidifier, keep the soil evenly moist, and move it away from heat vents and direct sun.
How do you care for a Boston fern indoors in winter?
Keep it in a cool spot with moderate, indirect light, water only when the soil is dry, and do not fertilize, as N.C. Cooperative Extension advises. Some paler color and leaf drop is normal.
Does a Boston fern need sunlight?
It needs bright light but not direct sun. NC State recommends bright, indirect light, and N.C. Cooperative Extension warns that a south-facing window can burn the frond edges.
Is Boston fern toxic to cats?
No. The ASPCA lists Boston fern as non-toxic, and NC State tags it non-toxic for cats, dogs and horses.