How to Plant and Grow Boston Fern

For decades, Boston ferns have been grown as a tropical accent plant both indoors and out. The robust plant is often seen spilling out of pedestal planters and hanging baskets, or brightening up patios and shady garden spots with its graceful, sword-shaped fronds.

In the wild, it thrives in wet, forested areas, so—whether you are planting it indoors or outdoors—give it high humidity and consistent moisture and it will reward you with long arching stems of spring-green foliage.

Where to Plant Boston Fern

In hardiness zones 9 to 11, Boston ferns can be grown as perennials, but they require plenty of water and are not drought tolerant. In these zones, choose a spot that is in full or partial shade where the fern will have protection from drying winds. These requirements are some of the reasons why covered patios are such popular places to plant Boston ferns.

Outside of zones 9 to 11, you can still grow Boston ferns, but you may have better luck growing it as a container plant that can be moved indoors when chilly weather (45 degrees Fahrenheit and below) arrives.

When and How to Plant Boston Fern

If you plan to plant your Boston fern outdoors, the best time to do it is in the spring or fall (Indoor Boston ferns can be planted any time of year.). Choose a spot for your fern with moist, well-draining soil and lots of shade. Dig a hole that is approximately the same depth and twice the width as the fern’s nursery container, then place the fern in the ground and fill in the area with soil and a bit of organic compost. You can also add mulch around the base of the plant to help keep the soil moist and create a more humid environment for the establishing plant. 

Boston Fern Care

Boston ferns are relatively easy to grow as long as you stay on top of three things—moisture, sunlight, and temperature control. Like most ferns, Boston fern needs high humidity to thrive. Outdoor ferns will want shade, temperatures between 65- and 75 degrees Fahrenheit, and regular watering to keep the soil consistently moist.

For indoor ferns, set your plant in indirect sunlight, mist it regularly, and set it on a tray of wet pebbles to create a humid atmosphere. If you ignore the plant’s need for humidity, you are likely to end up sweeping up small brown leaflets shed by a struggling plant.

Light

When growing Boston fern as a houseplant, place it in bright, indirect light (like an east-facing window) and give the pot a turn every now and then to ensure even growth. When grown in too much shade, a plant’s fronds will become dull and sparse. Too much sun, though, and fronds
will burn.

When growing Boston fern outside, make sure your plant is sheltered from direct sun and strong winds. As cool weather approaches, many Boston fern growers choose to bring their container-grown ferns indoors for the winter.

Soil and Water

Boston ferns love moist, well-draining soil with a pH of 5 to 5.5, so keep your fern’s soil (ideally a peaty, soil-based potting mix) consistently moist at all times. If the soil dries out, the plant will crisp up and drop many of its leaves.

Temperature and Humidity

Indoor temperatures typically suit the Boston fern—which thrives between 60 and 75 degrees Fahrenheit—just fine. As cool weather approaches, many Boston fern growers choose to bring their outdoor container-grown ferns indoors for the winter.

The most finicky thing about a Boston fern is its need for humidity—ideally levels above 80 percent. If you don’t want to live in a tropical greenhouse, you can keep the plant happy by regularly misting it and setting it on a tray of gravel or pebbles. This will allow the moisture to evaporate into the air around the plant without the danger of it getting its feet too wet.

Fertilizer

Boston ferns can benefit from some fertilization, and if you notice pale or yellowing leaves on your fern, it may crave some nutrients. Feed the plant with a water-soluble fertilizer every 4 to 6 weeks in the spring and summer (or more often if the plant requires it). Fertilization is not typically needed in the fall and winter months. Fertilize potted ferns with a houseplant formula at half-strength every month from spring to early fall.

Pruning

The Boston fern’s foliage consists of numerous small leaflets that, if allowed to dry out, fall off and leave wiry stems behind. If your Boston fern loses lots of its foliage, cut it back to about 2 inches in the spring and it will eventually regenerate to form a lush plant. Spring is also the best time to divide your Boston fern.

Potting and Repotting

When planting nursery starts, choose a pot that is large enough to allow room for growth, but not so large that the plant expends all its energy growing roots instead of foliage. A too-large pot also runs the risk of developing root rot since the plant will be too small to soak up all the moisture left in the soil after watering.

After you have chosen a pot, place some gravel in the bottom of the pot for drainage and partially fill it with a peat-based potting mix that contains perlite for added drainage. Tease the root ball apart so that the roots can spread to the edges of the container and place the plant in the pot. Fill in the pot with potting mix (do not pack it) and thoroughly water.

When transplanting or dividing your Boston fern, it’s okay to use a little force to get the plant’s roots dislodged from its container. It’s common for ferns to grow a little root-bound in containers. Water the plant first to make it more malleable and then wrap your fingers around the base of the fronds, invert the plant, and wiggle or tap the container against a hard surface until the plant comes free.

Pests and Problems

Boston ferns that are grown outside can fall victim to mealybugs, spider mites, and whiteflies. The juicy green leaves of the Boston fern are also a popular snack for snails, slugs, and caterpillars.

For both indoor and outdoor Boston ferns, blight and root rot can be a problem. Blight fungus may present as dark brown spots on the foliage, crown, and roots, but the problem lives in the soil. If this happens with a potted Boston fern, repot the plant in a sterilized pot with some fresh potting mix.

Root rot can develop if the soil remains too wet for too long. If root rot occurs with a potted fern, take your plant out of its container, repot it in a sterile container, and discard the diseased soil. If root rot
develops on an outdoor fern, take steps to amend the soil with organic matter to help it drain more freely. You can try dividing the plant, discarding the diseased sections, and replanting the healthier sections in a different location.

Propagation

One of the best ways to propagate Boston ferns is through division—which is best done in the spring. This will also prevent your fern from growing too root-bound. To divide your plant, remove the root ball from the soil and split it into two to four parts while keeping as many leaves intact as possible. Replant the divided ferns and water thoroughly.

Types of Boston Fern

You can find this plant in bright gold and a green-and-gold variegated variety, as well as with curly, wavy, twisted, drooping, and overlapping fronds. Some Boston ferns feature finely dissected leaflets that create a loose and airy feel.

Boston Fern

Nephrolepis exaltata ‘Bostoniensis’ is the standard type, grown as an elegant houseplant since Victorian times.

‘Dallas’ Fern

This variety of Nephrolepis exaltata was developed to tolerate lower light and drier air conditions than the common Boston fern. It is a compact plant, with fronds only about half the length of the species.

‘Fluffy Ruffles’ Fern

This smaller form of Nephrolepis exaltata has finely divided curled fronds.

‘Kimberly Queen’ Fern

Nephrolepis obliterata is a closely related species that is less sensitive to low humidity, so it holds up well in average room conditions.

Tiger Fern

This type is a variegated Boston fern with erratically marbled foliage in gold and green. This variety has large leaves that can get quite long.

‘Rita’s Gold’ Fern

Nephrolepis exaltata ‘Rita’s Gold’ is a lovely variety with stunning golden foliage that is especially bright on new growth.

Companion Plants for Boston Fern

It can be tricky to find companion plants for ferns given their preference for shady, moist growing conditions. Look to the places where Boston ferns grow wild for clues about plants that will thrive in similar conditions and opt for plants that also crave high levels of humidity, shade, and rain.

Bleeding Heart

Bleeding Heart plants are native to the shady woodland environment of the eastern United States and enjoy similar growing conditions to the Boston fern. Most bleeding heart types grow easily in zones 3 to 9, but to plant them alongside Boston fern, look for cultivars that can handle warmer climates, such as the Dicentra spectabilis ‘Gold Heart’ or the Dicentra cucullaria ‘Dutchman’s
breeches’ bleeding heart.

Browallia

The shade-loving browallia—which is most often grown as an annual—can be grown as a tropical perennial in zones 10 or 11. It prefers full to partial shade and moist, well-draining soil like the Boston fern. When browallia flowers, it produces bright blue, purple, or white blooms amid tidy mounds of green foliage

Caladium

The tropical caladium grows well in dappled shade where the bright sun won’t scorch their vibrant
leaves. They typically grow to about 6 to 12 inches in height and can get as wide as 24 inches across.  

Impatiens

Impatiens are pretty shade-garden annuals that bloom in bursts of blue, orange, pink, purple, red, white, or yellow. They make an excellent filler for garden beds and will thrive in rich, well-drained soil —particularly in climates where the temperature remains between 60 and 85 degrees Fahrenheit.