Boston fern care comes down to three things: bright indirect light, soil that stays evenly moist but never soggy, and humidity of around 50% or more. Keep it at about 16–24°C (60–75°F), away from radiators and cold draughts, and feed lightly only in spring and summer. Get the humidity right and the rest of Boston fern care is surprisingly simple.
Boston fern (Nephrolepis exaltata ‘Bostoniensis’) is one of the most rewarding houseplants you can grow, with long, arching fronds that look spectacular in a hanging basket. It is also honest: when the air is too dry or the soil dries out, it tells you quickly with brown tips and falling leaflets. This guide covers light, watering, humidity, soil, feeding, repotting, outdoor and winter care, the main varieties and how to fix common problems.
Patch Plants guides are written and checked by botanist Sawera Shahid, and with ferns we always start from the plant’s habitat. A Boston fern evolved on humid, shaded forest floors and tree trunks, so most care problems disappear once your home copies those conditions. You can read more about how we research our guides on the About Patch Plants page.
Key Takeaways
- Boston fern needs bright indirect light, evenly moist soil and humidity of about 50% or higher.
- Low humidity is the most common cause of brown tips and leaf drop, especially in heated homes in winter.
- Water when the top 2 cm of soil feels dry; never let the pot dry out completely or sit in water.
- A humidifier, a bright bathroom or a pebble tray works far better than misting alone.
- Keep it between 16–24°C and protect it from frost; it can summer outdoors in shade.
- Boston fern is non-toxic to cats and dogs according to the ASPCA.
- Curly types such as ‘Fluffy Ruffles’ need the same care; ‘Kimberly Queen’ and sword ferns cope better with drier air.
Boston Fern Quick Care Table
| Need | What Boston fern likes |
|---|---|
| Light | Bright indirect light; no harsh direct sun |
| Water | Keep evenly moist; water when the top 2 cm feels dry |
| Humidity | 50% or higher is ideal; below 40% causes browning |
| Temperature | 16–24°C (60–75°F); minimum about 10°C (50°F) |
| Soil | Rich, peat-free or coir-based mix with perlite for drainage |
| Feeding | Half-strength liquid feed every 4–6 weeks in spring and summer |
| Repotting | Every 1–2 years in spring |
| Pet safety | Non-toxic to cats and dogs |
What Is a Boston Fern?
Nephrolepis exaltata is a fern native to tropical and subtropical America, including Florida, Mexico, the Caribbean and parts of Central and South America. In the wild it grows on the forest floor, on rocks and on tree trunks, in warm, humid air under a canopy of leaves. The Boston fern, ‘Bostoniensis’, is a natural mutation with broader, more arching fronds, discovered in the 1890s in a shipment of sword ferns sent to Boston, which is how it got its name. It became one of the most popular parlour plants of the Victorian era.
That origin explains every care need: filtered light from the canopy, constantly moist air, regular rain and warmth all year. According to NC State Extension, Boston fern needs high humidity and consistently moist, well-drained soil, and dry air makes it more prone to scale and spider mites. Mature plants reach about 60–90 cm tall and wide.
Boston Fern Varieties
Standard Boston Fern (Nephrolepis exaltata ‘Bostoniensis’)
The classic form has broad, arching fronds that can reach 60–90 cm long on mature plants. It looks best in a hanging basket or on a plant stand where the fronds can cascade. All the care advice in this guide applies to it directly.
Curly Boston Fern (Nephrolepis exaltata ‘Fluffy Ruffles’)
‘Fluffy Ruffles’ is a compact cultivar with more upright fronds and wavy, ruffled leaflets. It suits shelves and tabletops better than hanging baskets. Care is the same as for the standard Boston fern; give it bright indirect light so the growth stays dense and the ruffled texture shows well.
Sword Fern and ‘Kimberly Queen’
The sword fern often sold as “Boston sword fern” is usually Nephrolepis cordifolia, a separate species with narrower, more upright fronds. It tolerates slightly drier air and occasional missed waterings better than a true Boston fern. It is invasive in some warm regions, including Florida and Hawaii, so keep it in pots there. ‘Kimberly Queen’ (Nephrolepis obliterata) is another upright fern that copes well with average home humidity, making it a good alternative if your air is dry. For a more delicate fern that needs even more humidity, see our maidenhair fern care guide.
Light Requirements for Boston Fern
Boston fern grows best in bright indirect light, the kind of filtered light it gets under a forest canopy. Too much direct sun scorches the thin leaflets and dries the large frond surface quickly, while too little light leads to sparse, pale growth.
- Best position: within 1–2 metres of an east- or north-facing window.
- Also fine: further back from a south- or west-facing window, or behind a sheer curtain.
- In dark winters: a small LED grow light for 10–12 hours a day helps keep growth dense.
| Too much light | Too little light |
|---|---|
| Pale, bleached or yellowing fronds on the window side | New fronds small, thin and pale |
| Crispy brown patches | Plant becomes open and sparse |
| Soil dries out very fast | Little or no growth in spring and summer |
Our complete guide to indoor light explains how to judge light levels by window direction.
How to Water a Boston Fern
Unlike snake plants or ZZ plants, Boston fern does not like to dry out between waterings. Its fine roots are used to steady moisture, and a pot that dries out completely leads to crispy fronds and heavy leaf drop. At the same time, waterlogged soil quickly causes root rot.
- Spring and summer: water when the top 2 cm of soil feels dry, often every 4–7 days.
- Autumn: roughly every 7–10 days as growth slows.
- Winter: roughly every 10–14 days, but never let the root ball dry out completely.
These are starting points; always check the soil with your finger, because pot size, room temperature and humidity change how fast it dries. Water thoroughly until it drains from the bottom, then empty the saucer after 15 minutes. Hanging baskets dry out faster than pots on the floor, so check them more often.
If brown tips continue even with good humidity, try rainwater or filtered water and flush the pot with plain water every few months, because a build-up of salts from tap water and fertilizer can scorch fern tips. Our complete watering guide and signs of overwatering guide go into more detail.
Humidity: The Most Important Part of Boston Fern Care
Humidity decides whether a Boston fern looks lush or tired. Many homes sit at around 30–40% relative humidity, and heated rooms in winter can drop lower, while Boston fern looks its best at about 50% or more.
| Relative humidity | What to expect |
|---|---|
| 50–80% | Ideal: dense, green, healthy fronds |
| 40–50% | Acceptable, with some brown tips |
| Below 40% | Browning, yellowing and leaf drop |
A cheap hygrometer shows your real humidity level. The most effective ways to raise it are:
- Humidifier: the most reliable option, especially during the heating season. Aim for 50–60% near the plant.
- Bathroom placement: a bathroom with a bright window is ideal, because shower steam raises humidity every day. See our best plants for your bathroom and low-light bathroom plants for companions.
- Pebble tray: a tray of pebbles and water under the pot adds a little local humidity; our DIY humidity tray guide shows how to make one.
- Grouping plants: placing several plants together creates a slightly more humid microclimate.
- Misting: only raises humidity for a few minutes, so use it as an extra, not your main method.
For more low-cost ideas, read our humidity hacks guide.
Temperature Requirements
- Ideal range: 16–24°C (60–75°F).
- Minimum: about 10°C (50°F); colder conditions damage the fronds.
- Avoid: cold window glass and draughts in winter, radiators and heating vents, and air-conditioning blowing directly on the plant.
Boston fern has no frost tolerance. It can only live outdoors all year in frost-free climates (roughly USDA zones 10–11).
Best Soil Mix for Boston Fern
The soil needs to hold moisture while still letting air reach the roots. A rich, open, slightly acidic to neutral mix works well:
- About 40% good-quality peat-free potting compost
- About 30% coco coir or peat moss for moisture retention
- About 20% perlite for drainage and air
- About 10% worm castings or fine bark for gentle nutrition and structure
A ready-made houseplant compost with an extra handful of perlite and coir also works. Always use a pot with drainage holes. Our soil mix guide for every type of plant lists fern mixes alongside other houseplants.
Fertilizing Boston Fern
Boston ferns are light feeders, and too much fertilizer causes brown tips and leaf drop.
- Spring and summer: balanced liquid fertilizer at half strength every 4–6 weeks.
- Autumn: feed less often, then stop.
- Winter: do not feed while growth is slow.
Read our guide to fertilizing indoor vs outdoor plants for seasonal feeding schedules.
Repotting and Propagating Boston Fern
Boston fern grows quickly and usually needs repotting every 1–2 years. Signs it is time include roots coming out of the drainage holes, soil that dries out within 2–3 days of watering, and slow growth in spring and summer.
Repot in spring into a pot only 3–5 cm wider, using fresh moisture-holding mix. This is also the best time to propagate: divide a large plant into two or three sections, each with healthy fronds and roots, or pot up the small plantlets that form on the thin runners. ‘Bostoniensis’ rarely produces reliable spores, so division and runners are the easiest methods. Keep new divisions warm, moist and humid while they settle.
Our guides on how to repot a plant, repotting mistakes to avoid and propagating houseplants at home cover each step.
Boston Fern Care Outdoors
Boston fern does very well outdoors in warm months, because outdoor air is usually more humid than indoor air. To care for a Boston fern outside, give it shade, steady moisture and shelter from strong wind.
- Best spots: a covered porch or veranda, under a tree with dappled shade, or against a north-facing wall.
- Watering: check every 1–3 days; hanging baskets may need water daily in hot, dry weather.
- Sun: avoid strong afternoon sun, which scorches the fronds even outdoors.
- Bringing it in: move it indoors before night temperatures fall below about 10°C. In the UK and northern Europe this is usually by September.
Check carefully for pests before bringing it back inside, and rinse the fronds if needed. For more shade ideas outdoors, see our guide to shade-loving plants for outdoor gardens and our tips on keeping pests away from outdoor plants.
Boston Fern Winter Care
Winter is the hardest season for Boston fern, because shorter days, cooler rooms and dry heated air arrive at the same time. These adjustments help it get through:
- Raise humidity: run a humidifier nearby or keep the fern in a bright bathroom.
- Move it away from heat: keep it well away from radiators, fires and heating vents, and off cold window sills at night.
- Water less, but don’t let it dry out: water when the top of the soil feels dry, roughly every 10–14 days.
- Give it the brightest indirect light you have: or add a grow light.
- Stop feeding: restart in spring when new fronds appear.
- Check for pests weekly: spider mites love dry winter air.
Some shedding of older fronds in winter is normal. Remove brown or yellow fronds at the base so new growth gets light and air.
Troubleshooting Common Boston Fern Problems
| Symptom | Likely cause | Fix |
|---|---|---|
| Brown, crispy tips | Low humidity, salt build-up, underwatering | Raise humidity, flush the soil, keep soil evenly moist |
| Brown or bleached patches | Direct sun | Move further from the window |
| Yellowing fronds | Overwatering, poor drainage, low light or old fronds | Check roots, empty saucers, improve light |
| Heavy leaflet drop | Soil drying out, sudden cold or heat, dry air | Water thoroughly, move away from draughts and heaters |
| Fine webbing, speckled fronds | Spider mites | Rinse fronds, raise humidity, treat with insecticidal soap |
| Little new growth | Root-bound, low light, cold | Repot in spring, increase light, keep above 16°C |
Brown dots in neat rows on the underside of fronds are usually spore cases, not pests. Fern leaflets can be sensitive to some sprays, so test any treatment on one frond first. For more help, see our guides to why leaves turn yellow, leaf curl, browning and droop and how to revive a dying plant.
Is Boston Fern Safe for Cats and Dogs?
Yes. The ASPCA lists Boston fern as non-toxic to both cats and dogs, which makes it a good choice for pet-friendly homes. Pets that chew any plant can still get a mild upset stomach, and hanging the fern out of reach also protects the fronds. Note that asparagus fern is not a true fern and is toxic to pets, so don’t confuse the two. Our cat-friendly plants guide and dog-friendly plants guide list more safe options, and the spider plant is another pet-safe trailing choice.
How to Style Boston Fern
- Hanging basket near a bright window: the classic display, letting the fronds cascade freely. See our hanging plants guide for more trailing ideas.
- Bathroom or kitchen: the extra humidity keeps fronds greener, as long as there is a window.
- Plant groups: combine it with other humidity lovers such as calathea, or contrast its soft texture with the upright leaves of a snake plant or ZZ plant placed nearby.
Our guides to styling indoor plants by room and decorating your bedroom with plants offer more display ideas.
Frequently Asked Questions
How often should I water my Boston fern?
Water when the top 2 cm of soil feels dry. That is often every 4–7 days in spring and summer and every 10–14 days in winter, but always check the soil, because the aim is evenly moist soil that never dries out completely or stays soggy.
Why is my Boston fern turning brown?
Brown, crispy tips usually mean the air is too dry or the soil dried out between waterings. Brown patches suggest direct sun, and widespread browning with leaf drop often follows a cold draught or a move next to a heater. Raise humidity and keep the soil evenly moist.
Are Boston ferns easy to take care of?
They are easy once humidity is sorted. In a bright bathroom or with a humidifier, Boston fern needs only regular watering and light feeding. In dry rooms, ‘Kimberly Queen’ or one of our best indoor plants for beginners may be easier.
Is Boston fern toxic to cats and dogs?
No. The ASPCA lists Boston fern as non-toxic to cats and dogs, so it is a safe choice for homes with pets. Keep it out of reach anyway to protect the fronds from chewing.
Can a Boston fern live outside?
Yes, in warm months. Place it in shade or dappled light, water more often and bring it indoors before nights drop below about 10°C. It can only stay outside all year in frost-free climates.
Final Thoughts
Boston fern breaks a few common houseplant rules: it wants evenly moist soil rather than drying out, softer light than many tropicals, and much more humidity than most homes provide. Treat it as a humidity plant first, and the rest of its care becomes a simple routine. Give it a bright bathroom, a humidifier in winter or a shady porch in summer, and it will reward you with full, arching fronds year after year. For more guides like this, browse our indoor plant care guides.
