How to Winter Boston Ferns

The popular houseplant we know as Boston fern – officially called Nephrolepis exaltata ‘Bostoniensis’ – helps brighten up a room. They can be moved outside for the summer and grown outside in USDA Zones 8 to 11. Left outside, they may need some winter protection. Moving them back inside is a process of several steps.


Indoor Growing Conditions

Boston ferns grown inside need a spot with plenty of bright but indirect light. Direct sunlight can damage leaves. Windows that get full sun should have a translucent shade or blind. The plants need warm temperatures and high humidity, especially in winter when the central heating system is on. Mist at least once daily. Water when the soil surface seems dry.

Temperature and Boston Ferns

The Boston fern is a semi-tropical plant, native to places like central America and Mexico. It has some specific temperature requirements:

  • Daytime temperatures averaging 75°F (24°C).
  • Nighttime temperature no lower than 55°F (13°C).
  • Lowest minimum temperature of 35°F (2°C).

Humidity can affect temperature tolerance – high humidity mitigates both excessively high and low temperatures for a short time.

Bringing Boston Ferns Inside for Winter

The shock of moving often makes the plant drop leaves. Prune back everything except the newest fronds to avoid a mess. Acclimate the plant – move it to the new location for a few hours at a time and gradually increase the time indoors. Withhold fertilizer during the winter – the plant is semi-dormant and doesn’t need to be fed.

Storing Boston Ferns Outside

If you don’t want to bother bringing them inside, you can store Boston ferns in containers outdoors. Find a place in an outdoor shed or garage where you can be sure the temperatures won’t drop lower than 55°F (13°C). Prune as directed above. If the plant is fully dormant, it won’t need light or fertilizer, but do water lightly about once a month.

Overwintering in the Garden

Boston ferns grown outside in the ground can handle winter conditions in USDA Zones 8 through 11. As with wintering indoors, prune the plant. Water enough to keep the soil slightly moist – this helps protect roots from freezes. If a hard freeze does threaten, cover the plant. Come spring, resume normal care, but don’t fertilize until the plant has been actively growing for at least a month.

When Spring Comes

Now that you’ve successfully wintered over your Boston fern, it’s time to get it ready for spring. Increase the amount of light it receives indoors or bring it back into the light if stored in a shed. Do this gradually – a few hours a day. Water more frequently, but don’t let it sit in soggy soil. Hold fertilizer for the first month of active growth.