Fern Plants Care: Light, Water and Humidity by Fern Type

Fern plants need bright but indirect light, soil that stays moist without standing in water, cool-to-moderate room temperatures and more humidity than most homes have. Clemson HGIC gives the core figures: moderate, indirect light, ideally close to a north-facing window; 60 to 70°F during the day and about 10°F cooler at night; and a porous, organic mix that lets excess water drain quickly.

The details change with the fern. Clemson notes that some ferns like to be kept almost wet while others should dry slightly between waterings, and that fine, thin-leaved ferns suffer most from dry air. So the first step is knowing which fern you have. A photo of a frond, top and underside, in PlantLens names the species.

Brooklyn Botanic Garden says ferns need plenty of bright, indirect light, and that direct sun burns their foliage, leaving it dry and brittle; it advises against south-facing windows. Clemson HGIC says the same about direct south or west windows. Growing Joy with Maria puts it simply: bright, indirect light, away from direct sun. Holly fern is the exception that copes with low light (Clemson HGIC).

Water according to the soil, not the calendar, because the sources give very different frequencies. Brooklyn Botanic Garden recommends daily watering to keep ferns moist in dry homes; Growing Joy with Maria says to keep the soil evenly moist and not let it dry out completely; Lively Root suggests every 7 to 10 days for Boston fern. What they share is the rule Clemson HGIC states: never let the mix dry out completely, and never let water stand in the pot, which damages the roots.

In practice, check the surface every day or two. When it just starts to feel dry, water until it drains, then empty the saucer. Button fern should never be allowed to dry out (Brooklyn Botanic Garden). A self-watering pot or a layer of sphagnum moss on the soil helps hold moisture (Growing Joy with Maria).

Brooklyn Botanic Garden recommends 40 to 50 percent relative humidity for ferns and notes that homes can be as dry as 5 to 10 percent. Growing Joy with Maria says delicate ferns such as maidenhair and heart ferns need 60 to 80 percent, while tougher types such as bird's nest tolerate less. Clemson HGIC gives maidenhair 50%.

What raises humidity: a humidifier that runs at least 12 hours without refilling (Brooklyn Botanic Garden); double-potting in damp sphagnum or peat moss (Clemson HGIC; Brooklyn Botanic Garden); and grouping plants or using a cloche (Growing Joy with Maria). Misting is widely recommended, but Penn State Extension found the rise lasts only until the water evaporates, often minutes, so it does little on its own.

Use a light, fluffy mix with organic matter and good drainage: Brooklyn Botanic Garden suggests adding peat moss or leaf mold, and coarse sand or perlite for drainage; Clemson HGIC suggests equal parts packaged houseplant mix and peat moss or leaf mold.

Feed lightly. Clemson HGIC says most ferns should be fertilised once a month from April through September at about half the recommended rate, not in winter, and not for six months after repotting, because ferns scorch when fed too heavily. Growing Joy with Maria says to fertilise only when you see new growth.

Repot when a fern begins to overcrowd its container, before it becomes root-bound (Brooklyn Botanic Garden). Division is the best way to propagate most ferns, done in early spring (Clemson HGIC), but bird's nest fern cannot be divided (Brooklyn Botanic Garden).

Clemson HGIC and Brooklyn Botanic Garden describe these common indoor ferns:

• Holly fern (Cyrtomium falcatum): an easy, adaptable fern that tolerates dry air, drafts and low light; about 24 inches tall (Clemson HGIC), up to 2 ft tall and 3 ft wide (Brooklyn Botanic Garden).
• Bird's nest fern (Asplenium nidus): easy to grow, with broad, undivided fronds in a vase shape, about 18 inches tall (Clemson HGIC).
• Squirrel's foot and rabbit's foot ferns (Davallia): furry rhizomes that creep over the pot edge, well suited to hanging baskets (Clemson HGIC; Brooklyn Botanic Garden).
• Caterpillar fern (Polypodium formosanum): recommended for indoors by Brooklyn Botanic Garden.
• Boston fern (Nephrolepis exaltata): needs high humidity to thrive (Clemson HGIC); see our Boston fern indoors guide.
• Button fern (Pellaea rotundifolia): about a foot tall and must never dry out (Brooklyn Botanic Garden).
• Maidenhair fern (Adiantum): difficult in most homes; needs 50% humidity and constantly moist soil (Clemson HGIC).
• Staghorn fern (Platycerium bifurcatum): grows on bark rather than soil and needs very high humidity that is hard to achieve in most houses (Clemson HGIC).

Growing Joy with Maria's beginner list is similar: bird's nest, rabbit's foot, Boston and lemon button, and staghorn, with maidenhair and heart ferns left for experienced growers.

Cut brown fronds off at the base; Growing Joy with Maria says ferns respond quickly with new growth, and Lively Root advises removing dead, discoloured fronds. Cutting is cosmetic, though, so check the cause:

• Browning at low humidity, especially in winter (Clemson HGIC).
• Dry, brittle, browning leaves from direct sun (Brooklyn Botanic Garden).
• Leaf scorch from heavy fertilising (Clemson HGIC).
• Root rot from overwatering or poor drainage (Clemson HGIC; Brooklyn Botanic Garden), where fronds collapse while the soil is wet.

Ferns produce spores instead of seeds, and Growing Joy with Maria notes they look like brown spots or scales on the fronds; NC State describes Boston fern spores as dark dots on the frond undersides. That resemblance matters, because scale insects are a real fern pest (Clemson HGIC). If you do spray, Clemson HGIC warns that some ferns are damaged by pesticides: read the label, test on a small area first and watch for injury. Brooklyn Botanic Garden notes that spores can even be collected from the underside of fronds and sown.

It depends on the fern. Tropical ferns sold as houseplants cannot take frost: NC State lists Boston fern as hardy only in USDA zones 10a to 13b, so in most of the U.S. it can summer outdoors in shade but must come in for winter. Nature Hills says to bring Boston ferns in when nights approach 50°F and put them back out when nights stay above 55°F. Hardy garden ferns are a different group of species, grown in the ground outdoors; the houseplant sources we used do not cover them.

Research and drafting for this page were done with the help of AI, and every figure was then checked line by line against the sources listed at the end of the page. Sources were opened on 2026-09-25. Where sources disagree, such as on how often to water or what humidity to aim for, we give each figure with its source rather than picking one. If you find a mistake, tell us and we will correct it.