What Temperature Is Too Cold for Ferns?

By Sophia Martinez · January 23, 2026

Ferns generally cannot tolerate temperatures below 45°F (7°C); most varieties begin to suffer damage when exposed to temperatures under 50°F (10°C), especially if prolonged or accompanied by cold drafts.

Understanding Cold Tolerance in Ferns

Ferns are ancient, non-flowering plants that thrive in moist, shaded environments. While they are adaptable, temperature plays a critical role in their health and longevity. Exposure to cold beyond their tolerance range leads to cellular damage, browning fronds, and eventual death.

Common Signs of Cold Stress in Ferns

Wilting or drooping fronds despite adequate moisture
Brown or blackened leaf tips and edges
Slow or stunted growth during expected growing periods
Mushy stems indicating frost-induced tissue breakdown
Complete collapse of foliage after sudden temperature drops

Fern Species and Their Temperature Thresholds

Different fern species exhibit varying degrees of cold hardiness. Tropical ferns are far more sensitive than temperate species. Knowing your fern type is essential for proper winter care.

Fern Species	Minimum Safe Temperature (°F)	Minimum Safe Temperature (°C)	Hardiness Zone	Notes
Boston Fern (Nephrolepis exaltata)	50°F	10°C	9–11	Sensitive to drafts; common houseplant
Maidenhair Fern (Adiantum spp.)	55°F	13°C	9–11	High humidity required; very cold-sensitive
Rabbit's Foot Fern (Davallia fejeensis)	50°F	10°C	10–12	Fuzzy rhizomes store water but not cold tolerant
Japanese Painted Fern (Athyrium niponicum)	35°F	2°C	4–8	Deciduous; tolerates light frosts
Ostrich Fern (Matteuccia struthiopteris)	30°F	-1°C	3–7	Cold-hardy; dies back in winter, regrows in spring
Holly Fern (Cyrtomium falcatum)	45°F	7°C	8–10	Tough leaves but still vulnerable below 45°F

Table data source:1, 2, 3

The data shows a clear distinction between tropical and temperate ferns. Tropical species like the Boston and Maidenhair fern require indoor protection when temperatures drop below 50°F, while hardy types such as the Ostrich and Japanese Painted Fern can survive brief exposure to freezing conditions. Gardeners in colder zones should select species accordingly.

Protecting Ferns from Cold Damage

Indoor Care During Winter

For tender ferns grown indoors or moved inside seasonally, maintaining stable conditions is key:

Keep away from cold windows, doors, and HVAC vents
Maintain temperatures between 60–75°F (15–24°C)
Use humidifiers to offset dry indoor air
Water consistently but avoid overwatering in cooler months

Outdoor Protection Strategies

If growing hardy ferns outdoors in borderline zones:

Apply mulch (e.g., straw or shredded bark) around the base before first frost
Use frost cloths or horticultural fleece during freeze events
Avoid pruning dead foliage until spring to insulate crowns
Plant in sheltered locations like north-facing walls or under tree canopies

Recovering Ferns After Cold Exposure

If your fern has been exposed to cold, take immediate action:

Move it to a warm, bright location without direct sunlight
Trim only completely dead fronds; leave damaged ones temporarily
Resume regular watering once soil begins to dry slightly
Wait 2–4 weeks before assessing new growth—recovery is slow

Note: Do not fertilize immediately after cold stress, as this can further damage weakened roots.

Frequently Asked Questions About Fern Cold Tolerance

Can ferns survive freezing temperatures?

Most tropical ferns cannot survive freezing temperatures. However, certain temperate species like Ostrich Fern and Japanese Painted Fern can tolerate brief exposure to 30–35°F (-1 to 2°C) with proper mulching and site selection.

What happens if my fern gets too cold?

Cold-damaged ferns develop brown or black fronds, limp stems, and may stop growing. Prolonged exposure leads to root damage and plant death. Recovery depends on the severity and duration of cold exposure.

Should I bring my fern inside for winter?

Yes, if you live in USDA zones below 9 and own tropical ferns like Boston or Maidenhair, bringing them indoors before nighttime temperatures drop below 50°F is essential for survival.

How do I protect outdoor ferns in winter?

For hardy outdoor ferns, apply a 2–3 inch layer of organic mulch around the base, avoid wet soils, and cover with frost cloth during extreme cold snaps. Do not cut back old fronds until spring.

Do ferns go dormant in winter?

Temperate ferns like Ostrich and Cinnamon ferns naturally go dormant in winter, dying back to the ground and regrowing in spring. Tropical ferns do not go dormant and require consistent warmth year-round.