It’s officially porch season! That means gussying up the front porch for curb appeal and porch sitting. Ferns are a classic finishing touch, and the Boston fern, also known as a sword fern, is the most iconic porch fern of them all.
Popular since Victorian times, the Boston fern features graceful, arching fronds that can reach 4 feet in length. It looks especially lovely in hanging baskets or on plant stands that show off its elegant, fountain-like shape.
A Boston fern is easy to grow in the right conditions. In addition to being a beloved porch plant, it’s a popular houseplant (and a pet-friendly one at that) that can thrive indoors 365 days a year. Outdoors in USDA Hardiness Zones 10 and warmer (find your zone here), it’s a fast-growing perennial.
In most of the country (USDA Hardiness Zones 9 and cooler), an outdoor Boston fern is treated a low-maintenance annual plant. But, with patience and dedication, a Boston fern can be overwintered and saved for next spring.
Ahead, everything you need to know to care for Boston ferns—whether you just bought one for your porch, want to keep one as a houseplant, live where you can grow them as perennials outside, or need tips to successfully see yours through winter in cold climates.
How do I keep my Boston fern happy?
Outdoors, Boston ferns aren’t fussy at all, as long as they receive ample light and moisture levels. They are especially happy when humidity levels are high during the steamiest summers.
How much sunlight do Boston ferns need?
Outdoors, Boston ferns prefer dappled shade, though they’ll tolerate a few hours of morning or late evening sun. Just don’t put them in direct sunlight, or they will fry.
The best place to keep a Boston fern outdoors is in a hanging basket or on a plant stand under the shelter of an overhang of a porch or portico.
Indoors, Boston ferns can be displayed in any room of the house in bright, indirect light, such as an east, west, or south-facing window. Or use an LED grow light if you don’t have the right lighting conditions. (Here are a few we recommend.)
How often do you water a Boston fern?
Boston ferns prefer to stay lightly but consistently moist. Typically, you’ll want to check them every few days, and water frequently to keep the soil damp.
That’s damp, not soaking wet! Water when the surface of the soil feels just barely dry, and don’t let it dry out completely.
Also, make sure the container has a hole in the bottom so excess water can drain out.
Will my Boston fern survive outside?
Boston ferns thrive outdoors in most of the country, unless temperatures dip into the 40s at night. If you expect a cold snap, you can cover them or bring them indoors (for tips on overwintering Boston ferns, keep reading).
In the warmer climates (USDA Hardiness Zones 10 to 11), they can grow outdoors year-round. They can also be planted in the ground among annuals and other perennials.
How do you keep Boston ferns looking good?
To keep your Boston fern looking its best, trim off any fronds that begin to brown at the base of the plant. Make sure to keep the soil lightly moist at all times. To give it a boost, fertilize with any all-purpose houseplant fertilizer during the growing season from spring to fall. Dilute the package recommendations by about ¼ to ½.
Indoors, your fern will need a little more TLC to look good. First, give it the right light (or it will drop lots of fronds). Then keep it watered (or it will drop lots of fronds). Seeing a pattern here? Boston ferns can be finicky inside your home, but if you give them good light and keep them moist, they can adapt.
Grouping your Boston fern with other houseplants, as well as running a small area humidifier, will help keep the humidity levels in the zone it prefers (40 to 50 percent). Get a humidity gauge if you want to see what your indoor levels are.
Finally, forget about misting your fern; no matter what you’ve read, that’s an old myth that just won’t die, and it doesn’t raise humidity levels any significant amount. Instead, keep it watered and it can adapt to dry indoor conditions.
How do you repot a Boston fern?
Boston ferns don’t mind being root-bound, so you typically won’t need to repot them if you’re only keeping them for one season. If yours survives the winter, however, you can repot if it shows signs of being too crowded in the pot, such as your fern needs watered more and more frequently.
Any type of pot is fine, except terra cotta, which tends to dry out too quickly—ferns don’t like that.
Make sure it has a hole in the bottom, or consider using a self-watering container, which will keep the soil at the right moisture level.
Ease the plant out of its old pot, size up about 2 inches in pot diameter, add your plant, and backfill with fresh potting soil. Any quality brand of potting soil is fine.
If you want to make a new plant, you can saw through the root ball vertically with a garden knife (it’s going to take some effort because the roots are fibrous), and separate into two sections. Then pot each piece into a new pot with fresh potting mix.
How do I keep a Boston fern overwinter?
If you live in a cold climate and can’t bear to part with your Boston fern in the fall, you can bring it indoors for the winter. However, it will require some patience. These plants will drop fronds as they adapt to indoor conditions.
Even if you give it good light and keep it moist, your Boston fern is likely going to get on your nerves at first. Worse case scenario: If you can’t keep up with the mess, cut the plant back to a few inches above the soil, and stash it in a cool place, such as your basement or garage. Water occasionally throughout the winter.
As daytime temperatures start creeping up into the 60s, you can place it outdoors again in bright, indirect light, resume watering and hope for the best.
If all of this seems like too much effort, compost your plant and buy a new one next year. One of the great things about Boston ferns is that they’re readily available and reasonably-priced, so you can treat yourself every spring if you don’t feel like dealing with a messy plant all winter.
