To overwinter your ferns indoors, it’s important to give them indoor conditions as close as possible to their natural outdoor environment.
Winter is the season to keep plants alive without encouraging lots of new growth.
How to Care for Ferns in Winter
When you bring your ferns indoors, the first thing to do is trim them. Remove any shoots growing at the outside of the container. Keep the strong, upright shoots in the middle. It’s safe to remove up to one-third of the fern. Give it a haircut, keeping the fronds about 10 inches long. If the fern is crowding its container, repot it into a container at least 3 inches larger.
Place the fern in a room that has plenty of light, making sure it’s in a place where the temperature won’t fall below 50 degrees Fahrenheit. Ferns that need more light should be placed in a sunny window. Spread old newspaper on the floor where you’ll place the fern to easily clean up any leaves that fall. You may need to snip off fronds that are going brown as well.
This winter “die back” is normal and not permanent. Come spring, the fern will put out new greenery.
Good drainage is important. Ferns like their soil moist, but never waterlogged. This is true in winter as in warm weather. The soil should be slightly dried out between waterings. Water ferns lightly, once weekly. Tropical ferns that need plenty of humidity, like Boston ferns, need to be misted with water every two or three days. Signs of over-watering are fronds turning yellow or drooping. That might indicate root rot.
However, too little watering can also make ferns droop. Poke a finger in the soil and if it’s dry past 2 inches, it should be watered.
Don’t fertilize ferns during the winter months. Start fertilizing again in late February or March. Use a water-soluble fertilizer, once a month.
Don’t worry if your fern looks scrawny as winter wears on. As long as it’s alive, it will bounce back when warm weather returns and you put it back outside.
Are you wondering if it’s a good idea to let your potted fern stay outdoors in winter? Consider what type it is. Is it a tropical fern, or a hardy one that can take the cold?
Do a little research to see if your climate will let it survive. A tropical fern that thrives outdoors during mild Florida winters won’t live through a snowy winter in Michigan.
Potted ferns that survive the cold are considered “hardy.” Examples are the Pacific Maidenhair, Western Sword, and Deer ferns. Hardy ferns tolerate hot summers too, which makes the hardy varieties ideal for greenery on your porch or balcony all year round. They can grow very large, some up to 6 feet or even larger. Even if your fern is said to be hardy in the cold, don’t trust it to survive a hard freeze. If the weather forecast calls for freezing temperatures, bring your potted ferns indoors ahead of time.
Good places to store your ferns for winter are a covered porch, a shed, even a basement if there are windows to let light in. If the container is too heavy to move, wrap it in bubble wrap or a blanket. Don’t allow the wrapping to touch the fern itself.
You might bring one or more ferns inside the house, if there’s room. A fern placed on a table looks lovely in any room, and will thrive if there’s indirect light around it. Remember that a warm, heated house can dry a fern out quickly. Keep the soil moist and either mist the leaves every few days, or keep a humidifier around it.
You may have a fern that was left out and withered under a cold blast. If it’s native to your region, it might still be alive under the soil. Bring it indoors and continue watering it lightly and not too often. It may surprise you with new greenery, come spring.
Moderate temperatures are key when bringing a fern indoors. Ferns like daytime temperatures below 70 degrees Fahrenheit. Night-time temperatures should be on the cool side: below 60 degrees Fahrenheit. 50-55 degrees is ideal.
How to Care for Boston Ferns in Winter
Let’s consider the lush Boston fern, one of the most popular ferns grown as houseplants. It grows well in warm, humid climates in USDA Zones 9-11. Keeping its soil and leaves moist, the Boston fern may also thrive in a drier environment, such as a heated house. Keep it in a sunny room, although not in direct sunshine from a window.
Boston ferns need high humidity, so either mist it often or keep it near a humidifier. It will pay you back by looking lovely, either in a pot or in a hanging basket.
Other Winter Ferns
For beauty that changes color over the growing season, consider keeping a hardy Autumn Fern, whose colors change from red to bronze and then to green. It’s hardy in USDA Zones 5 through 9. Other hardy ferns are the compact sword fern and the staghorn fern. Grow them in a planting medium made for epiphytic plants such as orchids, not potting soil.
Then there’s the tropical macho fern, whose fronds can grow 3 to 4 feet long. It’s a dominant plant and can overwhelm other plants in a container. If your winters are mild, plant a macho fern in a big basket hanging on the porch or other protected area. It will look spectacular. Macho ferns don’t do well in the cold, but you can take a clump off a growing one and bring it indoors to pot and keep over the winter. Treat it as you would any other fern.
A fern may live 100 years in the right environment. You may be able to hand your favorite fern down to the next generation!