Gardening How-to Articles

Caring for Ferns as Houseplants

What is it about ferns that makes them so appealing? Although they don’t flower or produce fruit or heady fragrance, ferns are a go-to choice for many gardeners in the outdoor landscape, where they tend to be easy to grow.

But why bring them indoors, as many houseplant lovers do? Out in the yard they are nearly maintenance free. Inside it’s a different story. They are very particular about their needs and will up and die if neglected. Yet people continue to be besotted, pampering countless ferns on their windowsills, in their bathrooms and kitchens, and anywhere in the home that they feel could use the softening effect of some lacy fronds.

The Victorians really led the way in bringing ferns indoors. Their widespread obsession with collecting and exhibiting these plants was so prevalent and intense that it became known as pteridomania. Most people grew their specimens in urns or terrarium precursors known as Wardian cases, but ferns also flourished in the elaborate glassed-in conservatories of the rich. Reinforcing the fad were myriad images of ferns that appeared as motifs on textiles, pottery, and jewelry. Around the same time, enthusiastic hybridizers also created hundreds of new fern varieties, many of which are still popular today.

The fern madness of the Victorians eventually gave way to a fixation on orchids, but the tradition of growing ferns indoors has lingered, and a multitude of varieties for that purpose continues to exist. Seemingly, there is a fern you can grow as a houseplant anyplace you can think of except, perhaps, the inside of a closet or under the bed.

Caring for Ferns

Ferns have a reputation for fussiness, and their cultivation requirements are quite specific. Still, with a little thought and attention, you can successfully grow and maintain them as houseplants. Experts advise analyzing your conditions carefully and then selecting a species that is well suited for the location you have in mind.

In general, for maximum growth and health, it is important to provide ferns with plenty of humidity, generous watering, lots of space, sufficient light without direct sun exposure, and rich, well-draining soil.

Moisture

Proper humidity can be one of the most difficult conditions to provide since most of us who live in temperate climates have central heat, which is very drying. Home moisture levels can be desertlike, as low as 5 to 10 percent relative humidity, well below the 40–50 percent levels recommended for ferns.

There are a few simple methods for countering that dryness. Daily watering will help. Resting potted ferns on water-filled saucers or trays that contain a layer of pebbles or broken crockery is another simple way of keeping the humidity high. Just make sure that the bottoms of the pots rest above the water, not in it. Soggy fern roots can lead to rot and untimely death. Another trick is to place ferns planted in clay pots inside a larger plastic pot lined with a damp, spongey medium such as peat moss. The clay pot will wick the moisture from the peat moss and help prevent the fern soil from drying out.

To grow ferns indoors, try to replicate the moist, low-light conditions where the thrive outdoors. Photo by Blanca Begert.

If more moisture is needed, the use of a humidifier near your plants is an option. Drugstore humidifiers are designed to hydrate people, not plants, so there are a few special features to look for when purchasing one. Generous run time is important—select one that can run continuously without refilling for at least 12 hours. Humidifiers have to be cleaned frequently to keep them from spewing salt, mold, or bacteria on your plants, so choose one with a simple design to streamline the chore.

You probably see fern fronds, or leaves, used as fillers in flower arrangements. But don’t let that make you think fern plants will tolerate being packed tightly against a begonia or peace lily in your home. Their delicate leaves are easily broken and they need plenty of freely circulating moist air to prevent damage and keep them sufficiently hydrated. This is an important point to remember if you decide to use a humidifier. Placing a fan nearby will help disperse the moisture-laden air and keep water droplets from landing on your plants, possibly causing blights and other distressing fern diseases.

Light

The issue of light for the indoor fern is fraught for many gardeners. I prefer not to know how many ferns I have killed simply because I thought the plant was the perfect answer to livening up a dark corner. Although ferns are happy residents of shade gardens outdoors, inside they require plenty of bright, indirect light. Exposure to direct sun will burn their delicate foliage, making it dry and brittle and browning the edges. Avoid southern exposure where ferns will be subjected to harsh solar rays.

Soil Mix and Containers

When planting your ferns, choose a light, fluffy soil mix that contains plenty of organic matter, but not enough to make the soil so heavy and dense that it does not drain well. Most packaged houseplant mediums should work well as long as they are rich in porous organic materials such as peat moss or leaf mold. Adding coarse sand or perlite will allow water to flow through freely.

Both plastic and clay pots are suitable for ferns, with those in plastic pots requiring less frequent watering. Pots should be large enough to accommodate the roots with an extra inch of space for further growth. Fern roots tend to be shallow, so short containers are best. Most ferns grow slowly but you should repot when they begin to overcrowd their containers, before they become root bound.

Choosing a Fern

Ferns are known to be one of the oldest groups of living things on earth, dating back more than 300 million years. Today’s ferns, the descendants of those ancient plants, include more than 10,000 living species, second only to angiosperms or flowering plants. With so many ferns to choose from, selecting the right one can be daunting. Below are some good species to start with, and all tend to be widely available.

Caterpillar Fern (Polypodium formosanum)

Also called the grub fern, this species gets both common names from its blue-tinged rhizomes that resemble the insects and grow on top of the soil and over the side of the pot. While this plant requires the specific growing conditions discussed above, it is popular with home gardeners because it can survive the neglect of insufficient watering better than most. The fronds may turn brown and the distinctive rhizomes shrivel but they can recover once proper moisture is restored.

Lacy Rabbit’s Foot Fern (Davallia fejeensis)

This fern is similar in form to the caterpillar fern with furry, animallike rhizomes that are above ground. Both varieties are shown off to excellent advantage in hanging pots. Rabbit’s foot fern also has a reputation for toughness and, like the caterpillar fern, can survive a certain amount of neglect.

Bird’s Nest Fern (Asplenium nidus)

This fern is an epiphyte in its native rainforest habitat, which means it grows on another plant instead of in the ground. It is quite handsome in a very un-fernlike way, with unusual straplike fronds that emerge from a dark crown or “bird’s nest.” Grown in a pot indoors, this plant will tolerate occasional lapses in watering and somewhat less humidity than other ferns.

Japanese Holly Fern (Cyrtomium falcatum)

A vigorous plant with shiny, spiky leaflets that resemble holly foliage, Japanese holly fern is hardy to USDA Zones 6 to 11 where it can be grown outdoors as a shade plant. Inside it is more forgiving than other ferns, tolerating less humidity, brighter light and cooler temperatures. It is also larger than many ferns, typically reaching 2 feet in height and 3 feet in width.

Button Fern (Pellaea rotundifoli)

A small plant with delicate, rounded leaflets, button fern has a low-growing horizontal habit and typically only reaches about a foot in height. This plant is particularly insistent on plenty of humidity and should never be allowed to dry out.

Whatever fern you choose, be sure to commit yourself to its care requirements and prepare to enjoy its beauty for years to come. If you decide to propagate your fern, you will have a number of options depending on what type of fern it is. The simplest method is division and works with most ferns except the bird’s nest type. Some ferns produce tiny versions of themselves, bulbils, that can be collected and planted.

Other ferns, which spread via under- or above ground stems called rhizomes, can be propagated by cutting off and planting a piece of the rhizome. Ferns produce spores rather than seeds, and spores can be harvested from their growing location on the underside of fronds and planted.

By successfully cultivating ferns you can congratulate yourself on helping to preserve a genus whose ancestors helped to sustain the dinosaurs and predated the arrival of more conventional garden plants by millennia.

Jeanne Rostaing contributed to BBG's Japanese-Style Gardens handbook and writes frequently for Gardenista.

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Image, top of page:
Fernery
An image of a fernery from the 1872 houseplant guide Window Gardening. Image from Internet Archive Book Images.
Caterpillar Fern
Polypodium formosanum (caterpillar fern). Photo by Forest & Kim Starr.
Rabbit’s Foot Fern
Davallia fejeensis (rabbit’s foot fern) in the Steinhardt Conservatory. Photo by Michael Stewart.
Bird's Nest Fern
Asplenium nidus (bird’s nest fern) in the Steinhardt Conservatory. Photo by Michael Stewart.
Japanese Holly Fern
Cyrtomium falcatum (Japanese holly fern) in the Steinhardt Conservatory. Photo by Michael Stewart.
Button Fern
Pellaea rotundifolia (button fern). Photo by David J. Stang.
Cinnamon Fern