Ferns are fabulous additions to your houseplant collection, patio pots, hanging baskets, and gardens. They make great household plants because of a unique property that allows them to release moisture into the air; this means that placing them around other moisture-loving plants and having them indoors will benefit everyone looking for a little more humidity, especially in the winter.
Learn how to properly care for ferns over the winter, whether indoors or outside.
How to Care for Ferns in the Winter
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For gardeners in cold climates, a number of perennial ferns are hardy and don’t require much in the way of winter care; all that’s needed is to remove spent fronds in late winter or early spring. At this point, tightly curled fiddleheads will likely already be poking up from the crown.
However, tropical ferns need different care during the cold season especially if they’ve resided outdoors during warmer months. Some examples of tender ferns for the summer garden than can be overwintered indoors include Boston, asparagus, staghorn, bird’s nest, and rabbit’s foot ferns.
Popular for More Than a Century
Boston ferns have enjoyed popularity since Victorian times when they were introduced as parlor plants.
Staghorn, bird’s nest and rabbit’s foot ferns are more often grown as houseplants. Staghorn ferns adapt to temperature ranges between 50-100ºF, so bring them inside if your winter dips below this. Also be sure to bring bird’s nest and rabbit’s foot ferns indoors when temperatures fall below 60ºF if they’re stationed outside.
Boston and asparagus ferns are two types of fern much more likely to find a place on porches and patios in hanging baskets or container arrangements. In cold climates they are often kept as annuals and discarded at the end of the season, but both can be overwintered indoors and moved back out in spring, ensuring they survive many years.
Plan to move these indoors when temperatures drop below 55ºF and follow these steps to keep these decorative ferns going season after season.
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Light
Boston ferns will tolerate shade when kept dormant in a garage or basement overwinter, or you can winter them as houseplants in a spot with indirect light; eastern or western facing windows are appropriate locations.
Keep asparagus ferns inside in a spot that receives bright but not harsh sunlight, as it can burn the frond tips. Asparagus ferns also do well in a cool greenhouse.
Temperature
Ferns are intolerant of frosts and freezing, so bring them in well before outdoor temperatures drop below 55ºF. Give them a cool location free from drafts and away from heating vents. They grow best when daytime temperatures do not exceed 72ºF, with nighttime temperatures around 60ºF.
Pruning
Light pruning gives plants more manageable shape and size for growing indoors where space may be limited. Always remove fern fronds at the base rather than trimming them back. Take out fronds that are overlong, straggly, brown, or yellowing. Do not remove more than one-third of the plant.
Watering
Before moving ferns indoors, spray down the entire plant including the undersides of the fronds to help remove insect pests and debris.
Keep soil consistently moist for ferns kept as houseplants. If you’re keeping a Boston fern dormant, water only when soil dries out.
Some browning and dropping of leaves is normal but in instances of significant dieback, place pots on a tray of pebbles with water to increase humidity or move the fern to a cooler location. Do not allow the bottom of the pot to sit in water, as this can lead to root rot.
Pests
Remove any debris that may have collected in the fronds and give them a gentle raking with your fingers to help remove insects. Ferns attract black aphids, scale, spider mites, mealybugs, and whitefly which may need to be eliminated with insecticidal soap.
Tips For Overwintering Ferns
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- Find out about the species of fern you want to grow. Many are ideal for outdoor shade gardens and require little care other then a bit of spring cleanup and dividing occasionally.
- You don’t need to replace your Boston and asparagus ferns every year. With a little care, these ferns can be overwintered in their containers and live for many years. In fact, Boston ferns were introduced as houseplants more than a century ago.
- Tender tropical ferns are perennial only in USDA zones 9 and higher depending on variety, and are almost always grown in containers in cold climates. While they can grow in the ground, temperature, lighting, and moisture requirements render them short-lived and impractical as garden plants.
- Ferns, both indoor and outdoor species, can be lightly fertilized during the growing season with a balanced, slow release product. All ferns are sensitive to salts, so drench fertilized plants annually to wash away salt residue.
