Nephrolepsis exaltata 'Bostoniensis', the Boston fern or sword fern, is a popular house plant that is loved for its arching green fronds. It looks especially good in a hanging planter or on a plant stand, where it can cascade over the sides. It will improve the air quality in your home, too – Boston ferns are ranked as one of NASA's top 10 air purifying plants.
The plant is so-called because it is said to have been discovered in a shipment of ferns sent from Philadelphia to Boston in the late 1800s. It was smaller than the other ferns in the shipment, with a more attractive shape, and was cultivated a house plant.
Sword ferns hail from swamps and rainforests in south America and the West Indies, which gives plenty of clues about the conditions that the Boston fern likes – a warm, humid atmosphere, moist soil and no direct sunlight. Boston ferns have a reputation for being a little tricky to grow, but if you get their care requirements right, they'll thrive.
How to grow Boston fern
Grow your Boston fern in a bright spot that's out of direct sun. It likes humidity, so put it in a steamy bathroom or mist the leaves a couple of times a week. Keep the compost moist (but not wet) at all times.
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Growing Boston fern: jump links
- Where to grow boston fern
- How to care for boston fern
- How to propagate boston fern
- Boston fern problem-solving
- Types of Boston fern to grow
Where to grow a Boston fern
Your Boston fern needs a bright or lightly shaded spot in a warm room – keep it out of direct sun and away from draughts and radiators. It likes plenty of humidity so a steamy bathroom is ideal.
How to plant a Boston fern
Your plant will be fine in the pot that it came in at first, but you can repot it every couple of years into a slightly larger pot when it starts to outgrow its container. Use a 50:50 mix of multipurpose and soil-based compost.
Caring for a Boston fern
Keep the compost moist (but not wet) at all times during spring and summer. Water when the top few centimetres of compost become dry in autumn and winter. Mist your plant a couple of times a week. Feed with a weak liquid feed once a month in spring and summer.
How to propagate a Boston fern
If you have plenty of patience, you can try cultivating the spores on the undersides of the leaves – wait until they are brown are crispy, then place on top of a tray of moist compost, misting them to keep them moist. If you can't remove the spores, you can also place sections of leaves, spore side down, on top of compost.
The easiest way to propagate a Boston fern is by division – take a large plant out of its pot and gently prise the rootball apart with forks, or slice through it with a bread knife. Pot up the new plants and water well.
Growing Boston fern: problem solving
- Brown leaves are nothing to worry about if they are at the base of the plant – it is normal for some of the older fronds to die back naturally. If the problem is widespread, the air may be too dry or your plant needs more water. The fronds also have a tendency to turn brown if they are repeatedly touched or disturbed.
- Dropping leaves are common on Boston ferns. You can rake your hand through the plant to clear them. Regular watering and misting will help prevent the problem.
- Pale leaves could be a sign that your plant need watering. It could also be in too bright a spot or it needs feeding.
- If fronds are turning yellow, the air may be too dry or too warm.
- Brown spots on the undersides of the leaves are naturally occurring spores and nothing to worry about.
- Round, white balls attached to the roots are nothing to worry about either – these are nodules that store water.
- You may notice spider mites, scale insects and mealybugs on the leaves.
Advice for buying Boston fern
- Check that you have the right conditions for a Boston fern – it needs a bright or lightly shaded spot with a steady, warm temperature and likes humidity
- You can buy Boston ferns at garden centres and nurseries, but for more unusual varieties, buy from a specialist house plant retailer or online
- Check that your plant has healthy, bright green leaves with no signs of pests or diseases
Where to buy Boston fern online
Varieties of Boston fern to grow
- Boston nephrolepsis 'Green Lady' is a widely available variety, with dark green fronds and a ruffled appearance. Height x spread: 75cm x 75cm