How Cold Can Boston Ferns Tolerate? Ultimate Guide

By Marcus Williams · January 24, 2026

Boston ferns can tolerate temperatures as low as 35°F (2°C), but prolonged exposure to cold below 45°F (7°C) may cause damage or death. For optimal growth, maintain temperatures between 60–75°F (15–24°C).

Understanding Boston Fern Cold Tolerance

Boston ferns (Nephrolepis exaltata) are tropical plants native to humid forests of the Americas and the Caribbean. While they thrive in warm, moist environments, many indoor gardeners wonder how much cold these popular houseplants can handle before suffering damage.

The critical threshold for Boston ferns is around 35°F (2°C). Below this temperature, cellular damage occurs due to freezing. However, even above freezing, extended exposure to temperatures under 45°F (7°C) can lead to chilling injury, leaf browning, and stunted growth.

Signs Your Boston Fern Is Too Cold

Cold stress manifests in several visible symptoms. Watch for these warning signs:

Yellowing or browning fronds, starting at the tips
Drooping or limp foliage despite adequate watering
Stunted new growth or complete cessation of development
Fungal issues due to slowed metabolism in cool, damp soil
Leaf drop, especially in sudden temperature drops

Why Cold Temperatures Harm Boston Ferns

As a tropical species, Boston ferns lack natural antifreeze mechanisms. Cold reduces metabolic activity, impairs water uptake, and increases susceptibility to root rot. Even brief exposure to chilly drafts from windows or air conditioning units can trigger stress responses.

Optimal Temperature Range for Healthy Growth

To keep your Boston fern lush and vibrant, aim for consistent temperatures within its ideal range:

Daytime: 65–75°F (18–24°C)
Nighttime: 60–65°F (15–18°C)
Humidity: 50–80%

Maintaining this environment mimics the fern's natural habitat and supports vigorous growth.

Temperature Tolerance Comparison: Boston Fern vs. Common Houseplants

Plant Species	Minimum Safe Temp (°F)	Minimum Safe Temp (°C)	Optimal Range (°F)	Frost Tolerant?
Boston Fern (Nephrolepis exaltata)	35	2	60–75	No
Spider Plant (Chlorophytum comosum)	35	2	60–75	Marginally
Snake Plant (Sansevieria trifasciata)	50	10	70–85	No
Pothos (Epipremnum aureum)	50	10	65–85	No
Zebra Plant (Aphelandra squarrosa)	60	15	70–80	No

Table data source:1, 2, 3

The data shows that while Boston ferns can survive brief dips to 35°F, they are less cold-tolerant than some common houseplants like spider plants, which share similar thresholds. In contrast, tropical species like zebra plants require warmer minimums. This highlights the importance of microclimate management indoors during colder months.

Protecting Boston Ferns from Cold Damage

Prevention is key when it comes to cold protection. Follow these best practices:

Keep away from drafty areas: Avoid placing near doors, windows, or AC vents.
Use thermal curtains: Insulate windows at night to reduce heat loss.
Elevate pots: Cold floors conduct chill; use plant stands or trays with pebbles.
Monitor indoor humidity: Dry air worsens cold stress; use a humidifier if needed.
Avoid outdoor placement in winter: Never leave outside when temps dip below 45°F.

Winter Care Tips for Boston Ferns

During winter, adjust care routines to compensate for lower light and heating systems:

Reduce watering frequency but maintain soil moisture
Mist regularly to combat dry indoor air
Rotate for even light exposure
Inspect for pests like spider mites, which thrive in warm, dry conditions

Frequently Asked Questions About Boston Fern Cold Tolerance

Can Boston ferns survive winter outdoors?

Boston ferns cannot survive winter outdoors in USDA zones below 9. In zones 9–11, they may overwinter with mulch protection, but frost will kill exposed fronds. In colder regions, bring them indoors before nighttime temperatures fall below 45°F (7°C).

What happens if my Boston fern freezes?

If a Boston fern freezes, ice crystals form in plant cells, causing irreversible damage. Affected fronds turn black and mushy. Trim damaged parts and move to a warm location. Recovery is possible if the rhizome remains alive, but full regrowth takes weeks.

Can I put my Boston fern outside in spring?

Yes, you can move your Boston fern outdoors in spring once nighttime temperatures consistently stay above 50°F (10°C). Acclimate it gradually over 7–10 days by increasing sun exposure slowly to prevent shock and sunburn.

Do Boston ferns go dormant in winter?

Boston ferns do not go fully dormant but often slow growth significantly in winter due to lower light and cooler temperatures. Reduce fertilization and watering slightly, but continue providing humidity and indirect light to sustain health.

How do I revive a cold-damaged Boston fern?

To revive a cold-stressed Boston fern, first trim dead or damaged fronds. Move it to a warm area with bright, indirect light and stable temperatures above 60°F (15°C). Increase humidity and water carefully—overwatering risks root rot. New growth should appear in 4–6 weeks if the root system is intact.