How to Keep Ferns Over the Winter: Expert Tips

By Priya Sharma · January 24, 2026

To keep ferns over the winter, maintain consistent moisture, provide bright indirect light, reduce watering frequency, and avoid cold drafts or temperatures below 45°F (7°C). Tropical ferns should be brought indoors before frost; hardy outdoor ferns benefit from mulch insulation. Proper humidity (40–60%) and pest monitoring are essential for survival.

Understanding Winter Challenges for Ferns

Ferns, especially tropical varieties like Boston or maidenhair, are sensitive to cold and dry indoor conditions during winter. When temperatures drop below 45°F (7°C), most non-hardy ferns suffer cellular damage. Indoor heating reduces humidity, increasing desiccation risk. Understanding these stressors is key to successful overwintering.

Common Winter Threats to Fern Health

Sudden temperature drops or exposure to frost
Low indoor humidity from heating systems
Overwatering in cooler soil conditions
Inadequate light during shorter days
Pest infestations (spider mites, scale) thriving in warm, dry air

Choosing the Right Location Indoors

Place ferns near east- or north-facing windows to receive bright, indirect sunlight. Avoid south-facing windows with intense midday heat or cold drafts from sealed windows. Ideal room temperatures range between 60–70°F (15–21°C).

Optimizing Humidity Levels

Ferns thrive in 40–60% relative humidity. During winter, indoor levels often fall below 30%. To compensate:

Use a cool-mist humidifier nearby
Place pots on pebble trays filled with water
Group plants to create microclimates
Mist foliage lightly in the morning (avoid if prone to fungal issues)

Watering and Soil Management

Reduce watering frequency in winter due to slower evaporation and growth. Allow the top inch of soil to dry slightly before rewatering. Always use well-draining potting mix with perlite or orchid bark to prevent root rot.

Signs of Improper Watering

Yellowing fronds: often overwatering
Crisp, brown edges: underwatering or low humidity
Mushy stems: advanced root rot

Fern Type	Min Winter Temp (°F)	Min Winter Temp (°C)	Light Needs (Winter)	Water Frequency (Weeks)	Humidity Preference
Boston Fern (Nephrolepis exaltata)	50	10	Bright Indirect	1–2	50–60%
Maidenhair Fern (Adiantum spp.)	55	13	Medium Indirect	1–2	60–70%
Rabbit's Foot Fern (Davallia fejeensis)	50	10	Medium Indirect	2	50–60%
Japanese Painted Fern (Athyrium niponicum)	0	-18	Partial Shade	Dormant	N/A (Outdoor)
Holly Fern (Cyrtomium falcatum)	45	7	Low to Medium	2–3	40–50%

Table data source:1, 2

The data shows tropical ferns require warmer conditions and higher humidity than hardy species. Boston and maidenhair ferns need more frequent watering and brighter light, while holly and rabbit's foot ferns tolerate lower moisture input. Hardy ferns like Japanese painted fern survive freezing by going dormant outdoors with mulch protection.

Fertilizing and Pruning in Winter

Avoid fertilizing during winter months when ferns enter semi-dormancy. Resume feeding in early spring with a balanced liquid fertilizer (e.g., 10-10-10) at half strength. Lightly prune dead or damaged fronds to encourage new growth once daylight increases.

Preparing Outdoor Ferns for Cold Climates

Hardy perennial ferns (USDA Zones 3–9) survive winter with proper mulching. Apply 2–3 inches of leaf mold, pine needles, or straw after ground cooling but before deep freeze. This insulates crowns without trapping excess moisture. Remove mulch gradually in spring to prevent crown rot.

Monitoring for Pests and Diseases

Dry indoor air encourages spider mites and scale insects. Inspect regularly under fronds and along stems. Treat early infestations with insecticidal soap or neem oil. Isolate affected plants immediately to prevent spread.

Frequently Asked Questions About Keeping Ferns Over Winter

Can I leave my fern outside during winter?

Only if it's a hardy species (e.g., Dryopteris, Athyrium) in USDA Zone 5 or colder zones with mulch protection. Tropical ferns must be brought indoors before nighttime temperatures fall below 50°F (10°C).

Why are my fern's leaves turning brown in winter?

Brown tips usually indicate low humidity or inconsistent watering. Increase ambient moisture using a humidifier or pebble tray, and ensure even soil moisture without sogginess.

How often should I water my fern in winter?

Most ferns need watering every 1–3 weeks depending on type and environment. Check soil moisture weekly; water only when the top inch feels dry. Overwatering causes root rot, especially in cool rooms.

Do ferns go dormant in winter?

Tropical houseplant ferns slow growth but don't fully dormant. Hardy outdoor ferns die back to the ground and resume growth in spring. Both types require reduced care compared to growing season.

Should I repot my fern before winter?

No, avoid repotting in winter. Repot only in spring when active growth resumes. Disturbing roots in cold months increases shock risk and slows recovery.