Ferns earn their keep in the garden and the living room. They release moisture into the air through their fronds, which makes them natural humidifiers: place them near other moisture-loving plants, or indoors in winter, and everyone benefits. That same moisture habit makes them vulnerable when the heat comes on, so the care routine changes when the season does.
The rules are simple once you know what you own. Hardy perennial ferns shrug off snow and need almost nothing from you until spring cleanup. Tender tropical ferns die at the first hard frost unless they come inside. Sorting the two groups before cold weather arrives is the whole game, and the principles match what works for overwintering garden plants indoors: inspect for pests, transition gradually, and match the care to the plant’s rest state.
Sort Hardy Ferns From Tender Ferns Before Frost
Not every fern needs winter protection. For gardeners in cold climates, a number of perennial ferns are fully hardy: all they need is to have spent fronds removed in late winter or early spring. By that point, tightly curled fiddleheads are usually already poking up from the crown. Many hardy ferns are ideal for outdoor shade gardens and need little care beyond that cleanup and an occasional division when the crown gets crowded. These ferns can stay put through snow, ice, and freezing temperatures.
Tender ferns are a different problem. Boston, asparagus, staghorn, bird’s nest, and rabbit’s foot ferns all count as tender tropicals, and every one of them is damaged or killed by frost. Boston ferns have been popular as parlor plants since Victorian times, and they still top the list of porch ferns that people want to save from year to year. Staghorn, bird’s nest, and rabbit’s foot ferns are more often grown as houseplants, but they still need to come in from patios and balconies when temperatures drop.
Temperature Thresholds That Matter
The trigger is temperature, and the thresholds vary by type. Staghorn ferns adapt to a range between 50 and 100 degrees F, so bring them inside when nights dip below 50. Bird’s nest and rabbit’s foot ferns should come indoors when temperatures fall below 60 degrees F if they are stationed outside. Boston and asparagus ferns move in when the thermometer drops below 55 degrees F. Frost and freezing are fatal to all of them, so plan the move well before the first freeze, not after it.
| Fern | Move indoors below | Winter plan |
|---|---|---|
| Hardy garden ferns | Stay outside | Cut spent fronds in spring |
| Boston fern | 55 degrees F | Houseplant or dormant |
| Asparagus fern | 55 degrees F | Bright indirect light |
| Staghorn fern | 50 degrees F | Warm room, mounted |
| Bird’s nest and rabbit’s foot | 60 degrees F | Warm room, houseplant |
Tender ferns are almost always grown in containers in cold climates. They can grow in the ground, but temperature, lighting, and moisture requirements make them short-lived and impractical as garden plants outside USDA zones 9 and higher. The pickiest ones live indoors year-round: growing maidenhair ferns indoors shows the humidity-heavy care these plants expect.
Bring Outdoor Ferns Inside the Right Way
Moving a fern indoors is a transition, not a relocation. Ferns tolerate drafts and heating vents poorly, and they grow best when daytime temperatures stay at or below 72 degrees F with nights around 60 degrees F. A cool room with steady conditions beats a warm room with temperature swings.
Inspect, Spray, and Quarantine
- Spray down the entire plant, including the undersides of the fronds, to remove insect pests and debris before it enters the house.
- Rake gently through the fronds with your fingers to dislodge hidden insects and collected debris.
- Keep the fern in a separate room for about a week to catch hitchhikers before they spread to other houseplants.
Ferns attract black aphids, scale, spider mites, mealybugs, and whitefly, most of which can be eliminated with insecticidal soap. Catching them at the door is far easier than treating an established infestation in a room full of plants. The same timing discipline you would use to overwinter canna lilies applies to ferns: move them in before the first frost and give them a cool, bright spot.
Light and Temperature Indoors
Light needs differ by species. Boston ferns tolerate shade if they are kept dormant in a garage or basement over the winter, or they can grow as houseplants in a spot with indirect light; eastern or western facing windows are appropriate locations. Asparagus ferns want bright but not harsh sunlight, which burns the frond tips, and they also do well in a cool greenhouse.
Dormant or Awake
Decide whether each fern will stay awake or sleep. A Boston fern kept dormant in a cool basement needs water only when the soil dries out. A fern kept as an active houseplant needs soil that stays consistently moist. Some browning and dropping of leaves is normal either way, but significant dieback is a signal to raise the humidity or move the plant to a cooler location. Never let the bottom of the pot sit in water, because that leads to root rot.
Give Indoor Ferns the Humidity They Need
Indoor winter air is the biggest killer of overwintered ferns. Heating systems dry the air, and ferns release moisture constantly, so they dry out faster than most houseplants. The goal is to replace what the plant gives off without soaking the roots.
Three Ways to Raise Humidity
- Pebble trays: set pots on a tray of pebbles with water in it, and refill the tray as it evaporates. Keep the pot bottom above the water line.
- Grouping: place ferns near other moisture-loving plants so their combined transpiration raises the local humidity.
- Room choice: bathrooms and kitchens hold more moisture than living rooms, so a bathroom window with indirect light is prime fern territory.
Misting helps in the moment but evaporates fast; trays and grouping give steady, round-the-clock results. Watch the fronds for feedback: if the tips brown and the plant loses more leaves than it grows, raise the humidity before you change anything else. Boston ferns are the classic example, and the routines in how to grow and care for Boston ferns transfer directly to keeping them alive indoors through the winter.
Watering follows the same logic as humidity. For houseplant ferns, keep the soil consistently moist, watering when the top inch feels dry and letting the excess run from the drainage holes. In winter, growth slows and the plant takes up less water, so check the soil before reaching for the watering can: soggy soil in a cool room is the fastest route to root rot.
Care for Tropical Houseplant Ferns Through the Cold Months
Staghorn, bird’s nest, and rabbit’s foot ferns are more often grown as houseplants year-round, so winter care for them is about holding conditions steady rather than managing a transition.
Staghorn, Bird’s Nest, and Rabbit’s Foot Indoors
Staghorn ferns adapt to temperatures between 50 and 100 degrees F and are often grown mounted on boards or in wire baskets. Keep them in a warm room, water when the mount dries out, and give them indirect light. Bird’s nest and rabbit’s foot ferns want the same warmth with soil kept consistently moist. The mounting and watering details in how to grow and care for staghorn ferns matter even more indoors in winter, when the air is drier and growth slows.
Prune, Feed, and Watch for Salt
Light pruning keeps plants at a manageable size and shape for indoor space. Always remove fern fronds at the base rather than trimming them back, and take out fronds that are overlong, straggly, brown, or yellowing. Never remove more than one-third of the plant.
Ferns can be lightly fertilized during the growing season with a balanced, slow-release product. All ferns are sensitive to salts, so drench fertilized plants annually to wash away salt residue from the soil. Skip the fertilizer in deep winter, when growth is slow and the plant is not taking up nutrients.
Move Ferns Back Outside When Spring Arrives
When the risk of frost passes, reverse the process gradually. A fern that goes straight from a warm room into full sun will burn, and one that goes out during a cold snap will stall. Hardening off over two weeks solves both problems.
Hardening Off Over Two Weeks
- Start in full shade for one to two hours on a mild day.
- Add an hour of outdoor time each day, moving gradually toward the plant’s summer spot.
- Bring plants back in at night until overnight lows stay above 55 degrees F.
- Repot or divide before the growth flush if the fern outgrew its container over the winter.
Early spring is also the time to remove spent fronds from hardy garden ferns that stayed outside all winter. Divide crowded crowns and refresh the soil in containers before the growing season takes off. Lifting a crowded fern, splitting the crown into sections with a sharp knife, and potting each section in fresh mix keeps the plant vigorous and gives you free divisions for other beds. With the transition handled, the same ferns come back inside next fall with years of life ahead of them.