Boston fern, also known as sword fern, is a popular fern species that grows in many tropical areas around the world. In North America, it is considered a classic houseplant and is easy to care for, as it doesn’t require a lot of sunlight and can live on for years. It also purifies the air and increases humidity in a room. Outdoors, this perennial plant thrives in swampy, humid, and forested areas, and makes a good choice for partial-shade gardens in places like Southern California or Florida.
Its sword-shaped, blue-green foliage contains tiny leaflets and grows erect, arching only when fronds grow larger, which can reach 4 feet long and 6 inches wide. Like several other fern species, Boston fern grows quickly when young and becomes more of a slow-grower as it matures. It is best planted outdoors in the fall or spring or indoors year-round.
Boston ferns and sword ferns are two of the most popular ferns grown as houseplants and in gardens. With their graceful, arching fronds, it’s easy to see why. But what exactly is the difference between the two?
Boston Fern Overview
The Boston fern (Nephrolepis exaltata ‘Bostoniensis’) is a cultivar of the species Nephrolepis exaltata, which is native to tropical regions around the world. The cultivar was discovered in 1894 as a mutation of the sword fern in a shipment to Boston, hence the name “Boston fern.”
Some key characteristics of the Boston fern
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Fronds (leaves) can reach up to 6 feet long They arch gracefully downwards
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The fronds are made up of many small leaflets or pinnae. The pinnae are typically 1-3 inches long.
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Thrives in warm, humid environments. Makes an excellent houseplant when humidity is provided.
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Tends to be a vigorous grower with a spreading, vining growth habit.
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Rarely or never produces spores. Relies mainly on division for propagation.
Sword Fern Overview
The sword fern (Nephrolepis exaltata) is the parent species of the Boston fern. It occurs naturally across much of the tropics worldwide. Some key differences:
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Fronds can reach 5 feet long. Also arch gracefully.
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The pinnae are larger, typically 3-8 inches long. More widely spaced along the rachis (stem).
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Growth habit is upright and vase-shaped rather than spreading/vining.
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Capable of reproducing via spores. Spore cases visible on the underside of mature fronds.
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Tends to prefer more shade and moisture compared to the Boston fern.
How to Distinguish Boston Ferns and Sword Ferns
Here are some tips for identifying between Boston ferns and sword ferns:
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Check the pinnae size. Boston fern pinnae are 1-3 inches long while sword fern pinnae are 3-8 inches.
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Look for spore cases on the underside of mature fronds. Boston ferns rarely produce spores but they are common on sword ferns.
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Examine the growth habit. Boston ferns have a vining, spreading habit while sword ferns grow in an upright, vase shape.
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Consider the environment. Sword ferns prefer more shade and moisture compared to Boston ferns.
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Check the bases of the fronds. Boston fern fronds emerge singularly while sword fern fronds often arise in clumps.
Caring for Boston Ferns vs Sword Ferns
Both Boston ferns and sword ferns require similar care as houseplants:
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Bright, indirect light. Avoid direct sun. Sword ferns prefer lower light than Boston ferns.
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High humidity. Mist frequently or use a humidifier.
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Moist soil. Allow to partially dry between waterings. Avoid soggy conditions.
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Warm temperatures between 65-80°F.
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Occasional fertilization during growth periods.
Boston ferns can tolerate slightly drier air and brighter light than sword ferns. Prune back dry fronds as needed to maintain an attractive appearance. Propagate by dividing crowded clumps.
While similar in appearance, Boston ferns and sword ferns can be distinguished by frond and pinnae size, growth habit, spore production, and preferred growing conditions. Both make excellent easy care houseplants with proper humidity, light, water, and temperatures provided. Observe the differences and pick the one that best suits your environment and tastes!
Water
Keep the soil lightly moist during the spring and summer growing months with once-weekly watering for houseplants and more frequently for outdoor Boston ferns in warm climates. Water every other week during fall and winter dormancy. Fronds may droop in dry soil.
Propagating Boston Fern
Boston fern is very easy to propagate by division. This method is good to use for a fern that has outgrown its pot or is taking over a garden space. Take these steps in the spring.
- Gather a sharp pair of garden shears, a garden trowel (for indoor plants), a spade shovel (for outdoor plants), a pot, and potting soil (for indoor plants only).
- Carefully separate a section of your fern with healthy roots attached. Use a garden trowel to separate indoor plants, and a spade shovel to carefully pull apart outdoor plants. Smaller sections can be divided and established, as well.
- Fill a pot halfway full with potting soil (for indoor plants) or dig a new hole in the garden (for outdoor plants).
- Plant your division into either the mix or the ground, taking care to fully cover the roots when you backfill the hole with soil.
- Water the new division, and keep the soil lightly moist at all times. Keep indoor plants in a warm spot away from drafts and temperature fluctuations, and out of direct sunlight.
- After a few weeks, gently pull on the base of the fronds. If you feel resistance, you know your fern has taken root.
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FAQ
Is Boston fern the same as sword fern?
Nephrolepis exaltata, known as the sword fern or Boston fern, is a species of fern in the family Nephrolepidaceae.
What is the difference between a fern and a Boston fern?
A “fern” is a broad category of vascular plants, while a Boston fern is a specific type of fern, Nephrolepis exaltata ‘Bostoniensis’, known for its arching, feathery fronds.
Do sword ferns like sun or shade?
Sword ferns generally prefer shade or partial shade.