The Boston fern (Nephrolepis exaltata), also known as the sword fern, is a popular fern species that grows in many tropical areas around the world. It is also commonly kept as a houseplant, especially because it doesn’t have high sunlight needs. The foliage of this fern remains evergreen. Its sword-shaped, blue-green fronds with many tiny leaflets are erect and arch as they grow larger. Like several other fern species, the Boston fern is a fairly slow grower and is best planted in the fall or spring.
|Botanical Name||Nephrolepis exaltata|
|Common Names||Boston fern, sword fern, ladder fern, boss fern|
|Plant Type||Herbaceous, perennial|
|Mature Size||2–3 feet tall and wide|
|Soil Type||Moist, well-drained|
|Hardiness Zone||10–12 (USDA)|
|Native Area||Americas, Africa, Polynesia|
Boston Fern Care
Boston ferns appreciate a little TLC. They like warm and humid conditions. And they don’t enjoy temperature extremes, either outside or from drafts, air conditioners, and heating vents indoors. It’s important to maintain stable growing conditions for Boston ferns, as any element to their care that’s out of whack can quickly damage the plant.
Plan to water frequently to prevent the soil from drying out. And fertilize from spring to fall when the plant is actively growing. Regularly misting your fern or using other means to raise humidity also is typically a must unless you live in a very humid climate. While pruning typically isn't a major chore, you should remove dead fronds as needed to keep the plant looking attractive. Overall, these plants don't have any major pest or disease problems as long as their growing conditions are met.
Watch Now: How to Grow and Care for a Boston Fern
Boston ferns do best in bright, indirect light. Too much shade can result in sparse fronds that aren’t their typical bright color. And too much sun can burn the fronds. So both outdoors and indoors, make sure direct sunlight won’t hit your plant.
These ferns like organically rich, loamy soil with good drainage. Poorly drained soil can cause root rot and ultimately kill the plant. For container Boston fern plants, use a peat-based potting mix.
To successfully grow Boston ferns, it is key to keep the soil lightly moist (but not soggy) at all times. If the soil begins to dry out, the fern’s foliage can quickly dry out and drop off the plant. During the fall and winter months, slightly reduce watering, as the plant is not actively growing. But if you notice the fronds getting dry, increase the amount of water you are giving the plant.
Temperature and Humidity
Boston ferns prefer mild temperatures between roughly 65 and 75 degrees Fahrenheit. They can’t tolerate either extreme heat or extreme cold. Temperatures above 95 degrees Fahrenheit can harm them, as can temperatures below 35 degrees Fahrenheit. High humidity also is critical for Boston ferns. They thrive in humidity levels of above 80 percent. To raise the humidity around your fern, set it on a tray filled with water and pebbles. Also, regularly mist the plant. If it’s not getting enough humidity, the tips of the fronds will begin to turn brown, which can eventually overtake the whole frond (and plant) if the humidity doesn’t increase.
From the spring to early fall, feed your Boston fern with a liquid houseplant fertilizer at half strength once a month. No fertilization is necessary over the late fall and winter months.
Boston Fern Varieties
There are several varieties of Boston ferns that vary somewhat in appearance, including:
- Nephrolepis exaltata 'Compacta': This is a shorter, more compact, and more upright version of the main species plant.
- Nephrolepis exaltata 'Florida Ruffle': A medium-size cultivar, it has feathery, ruffled fronds.
- Nephrolepis exaltata 'Golden Boston': Yellow-green fronds adorn this variety.
- Nephrolepis exaltata 'Rita's Gold': This is a compact plant with chartreuse fronds.
- Nephrolepis exaltata 'Fluffy Duffy': A small, dense fern, it has finely textured, feathery fronds.
Propagating Boston Ferns
Boston ferns are very easy plants to propagate by division. When repotting in the spring, carefully cut off a section of the fern with healthy roots attached. Even very small sections can become established as new plants with the proper care. Plant your division in fresh potting mix, and make sure to keep the soil lightly moist at all times. Also, keep the plant in a warm spot away from drafts and temperature fluctuations and out of direct sunlight. Once you feel resistance when gently pulling on the base of the fronds, you'll know it has taken root.
Potting and Repotting Boston Ferns
Pot Boston ferns in a container with ample drainage holes that's slightly larger than the plant's root ball. Once the roots are poking out of the soil, it's time to repot. Another telltale sign that the fern is out of space is if it's not growing as much as it normally does. Repotting is best done in the spring. Select just one container size up. Gently remove the fern from its old pot, and replant it at the same depth in the new pot using fresh potting mix.