Are Boston Ferns Perennials? Yes, Here's Where and How

By Emma Johnson · January 24, 2026

Boston ferns (Nephrolepis exaltata) are perennial plants in USDA hardiness zones 9 through 11, where they survive year-round outdoors. In colder climates, they are often grown as indoor houseplants and can live for many years with proper care.

Understanding Boston Ferns as Perennials

Boston ferns are naturally perennial in warm, humid climates. This means that under the right conditions, they return each growing season and can live for decades. Their longevity depends heavily on environmental factors such as temperature, humidity, and light exposure.

What Makes a Plant Perennial?

A perennial plant lives for more than two years, regrowing each spring from its root system. Unlike annuals, which complete their life cycle in one season, perennials have evolved to survive seasonal changes.

Perennials typically die back in winter but regenerate from roots in spring
They require dormancy periods or consistent warmth depending on species
Hardiness zone compatibility is crucial for outdoor perennial survival

Growing Boston Ferns Outdoors: Climate Considerations

Boston ferns thrive outdoors only in regions without freezing temperatures. They are native to tropical and subtropical areas, including parts of Florida and Central America.

USDA Hardiness Zones for Boston Ferns

The U.S. Department of Agriculture (USDA) classifies plant hardiness by zone. Boston ferns are considered perennials in zones 9–11:

USDA Zone	Minimum Temperature (°F)	Boston Fern Survival	Recommended Use
9	20–30°F (-6.7 to -1.1°C)	Limited outdoor survival; may die back in cold winters	Outdoor in sheltered areas; mulch heavily
10	30–40°F (-1.1 to 4.4°C)	Year-round outdoor growth possible	Perennial landscape use
11	40–50°F (4.4 to 10°C)	Thrives outdoors year-round	Ideal for permanent planting
Below Zone 9	<20°F (-6.7°C)	Not cold-tolerant; will not survive winter	Indoor container use only

Table data source:USDA, RHS

Data shows that Boston ferns can persist outdoors only where winter temperatures remain above 20°F. In zones 10 and 11, they act as true perennials, returning each year. Below zone 9, they must be brought indoors or replanted annually.

Indoor Care for Long-Term Boston Fern Health

In colder climates, Boston ferns are grown as indoor perennials. With proper care, they can live for 10–15 years or longer.

Essential Indoor Growing Conditions

Light: Bright, indirect sunlight—avoid direct sun which scorches fronds
Humidity: Maintain 50% or higher; use a humidifier or pebble tray
Watering: Keep soil consistently moist but not soggy
Soil: Well-draining, peat-based potting mix with perlite
Fertilizer: Balanced liquid fertilizer every 4–6 weeks during growing season

Common Challenges and Solutions

Indoor Boston ferns often suffer from low humidity and improper watering.

Issue	Causes	Solutions
Brown leaf tips	Low humidity, dry soil, fluoride in water	Increase humidity, use filtered or rainwater
Yellowing fronds	Overwatering, poor drainage	Allow top inch of soil to dry slightly between waterings
Dropping leaves	Sudden temperature change, drafts, underwatering	Maintain stable environment, avoid cold air

Propagation and Renewal

To extend the lifespan of your Boston fern, propagation helps maintain vigor. The most effective methods include:

Division: Split root ball in spring every 2–3 years
Stolons: Press runners into moist soil to root new plants
Spores: Advanced method using spore dust from mature fronds

Frequently Asked Questions About Boston Ferns as Perennials

Are Boston ferns perennials in all climates?

No, Boston ferns are only perennials in USDA zones 9–11. In colder zones, they cannot survive winter outdoors and must be grown as indoor houseplants to persist long-term.

How long do Boston ferns live indoors?

With proper care, indoor Boston ferns can live 10 to 15 years or more. Regular repotting, high humidity, and consistent moisture contribute to their longevity.

Can I grow Boston ferns outside year-round in zone 8?

Generally no. Zone 8 experiences winter temperatures below 20°F, which will kill Boston ferns. They can be grown outdoors in summer but must be brought indoors before frost.

Do Boston ferns come back every year?

Yes, in suitable climates (zones 9–11), Boston ferns die back in cooler months but regrow from their rhizomes in spring. Indoors, they remain evergreen year-round if cared for properly.

What’s the best way to overwinter a Boston fern?

Bring it indoors before temperatures drop below 50°F. Place in bright, indirect light, maintain humidity, and reduce watering slightly during winter dormancy. Avoid heating vents and cold drafts.