Boston Fern Care - Growing Nephrolepis Exaltata

by Max - last update on October 27, 2019, 9:48 pm
Boston Fern

Boston Ferns make provide a fresh, healthy look to your home or garden, but they have rather strict rules. Always remember to keep them well-watered, out of extreme temperatures, and in a place where they can receive dappled light most of the day. Take care of these criteria and you will have a beautiful houseplant in your home. 

Find about more about how to care for this interesting plant below.

Boston Fern Quick Overview

Boston Fern Quick Facts

Origin South and North America
Family Lomariopsidaceae
Scientific Name Nephrolepis exaltata 'Bostoniensis'
Type Evergreen fern
Common Name Boston fern, sword fern, ladder fern
Toxicity Not toxic
Light Bright, indirect light to partial shade
Watering Maintain moist soil
Humidity High humidity
Pests Spider mites, mealybugs, slugs

 

Varieties

The Boston fern, scientifically known as ‘Bostoniensis,’ is a cultivar of the Sword fern, Nephrolepis exaltata. Other cultivars of this plant exist which are very similar to the Boston fern.

Nephrolepis exaltata ‘Golden Boston’

Nephrolepis exaltata 'Golden Boston '
Nephrolepis exaltata 'Golden Boston ' - Credit to David J. Stang

This cultivar features fronds in a golden yellow-green color.

Nephrolepis exaltata ‘Whitmanii’

Nephrolepis exaltata ‘Whitmanii’
Nephrolepis exaltata ‘Whitmanii’ - Credit to David J. Stang

This variety has a lower humidity requirement, and its fronds are finer and more delicate, with a feather-like appearance.

Nephrolepis exaltata ‘Fluffy Ruffles’

Nephrolepis exaltata 'Fluffy Ruffles'
Nephrolepis exaltata 'Fluffy Ruffles' - Credit to David J. Stang

This cultivar has fronds with a very fine texture which give a fluffy, feather-like appearance. The fronds divide and overlap to create a very full and dense plant.

Nephrolepis exaltata 'hawaiiensis'

Nephrolepis exaltata hawaiiensis
Nephrolepis exaltata 'hawaiiensis' - Credit to dweickhoff

As the name suggests, this variety is native to Hawaiʻi and can be recognized easily with its black dots running across its fronds.

Nephrolepis exaltata ‘Massii’

This variety is almost identical to the Boston fern, but its fronds are a darker shade of green.

Nephrolepis exaltata ‘Dallas’

This is a compact cultivar taht is aesthetically similar to the Boston fern, but it is able to tolerate lower humidity levels and does not require as much light to thrive. It grows rapidly and has a spreading habit.

Boston Fern Care

Boston Fern Care

Watering

Boston ferns need to be grown in continually moist soil, so a well-draining soil is essential to prevent problems with waterlogged soil and root rot. For Boston ferns kept as houseplants, allow the top inch or two of soil to dry out before you water it again. Some people recommend routinely soaking the plant heavily once a month to ensure its water needs get met.

Outdoor Boston ferns will have different requirements based on their conditions, but they are not drought tolerant and should never be allowed to dry out. In the summer you can expect Boston ferns kept in containers to need watering every day, or sometimes twice a day, while Boston ferns planted directly in the ground will not need irrigation as frequently as the roots can seek out moisture deeper in the soil. Be careful with Boston ferns grown in positions of shade, as soil can more easily become waterlogged and boggy, while still aiming to maintain moist soil (North Carolina State University Extension).

Light

Boston Fern needs bright indirect light
Boston Fern needs bright indirect light

The lighting requirements of your Boston fern will depend on whether you are growing it indoors or outdoors, as well as the season. In general, Boston ferns need a few hours of bright, indirect light each day in order to thrive, but too much intense light will scorch the fronds, so it’s important to also offer some shade. A position of dappled light would be best for the Boston fern as a houseplant as this mimics the natural environment of the plant. You can recreate this in your home by setting the plant near a window with a sheer curtain or blind so that it gets the light it needs without risking scorched foliage.

During fall and winter when the sun isn’t as strong, the Boston fern can tolerate some direct light, but in summer when sunlight is intense, you will need to move the plant to a more shaded and protected position. Boston ferns kept outdoors should be in partial shade to almost full shade, with just an occasional bout of sunlight. This is because the plant likes to be kept cool, and shade will help to shelter it from heat and protect the fronds from burning. This makes the plant ideal for brightening up dark corners of gardens where many plants would be unable to grow.

Temperature

Boston ferns like to be grown in cool but not cold climates
Boston ferns like to be grown in cool, but not cold climates

Boston ferns like to be grown in cool, but not cold climates. The ideal temperature for this plant is between 60-75º F, making it ideal for growing year-round as a houseplant. It can be kept outside during spring and summer as long as it is in a sheltered position where it won’t get too hot. The plant can tolerate short bouts of cold weather, but not sustained temperatures of less than 50º F. Frost will kill the plant back to the ground, but it will recover in spring, so it can be kept outside all year round if you wish.

You also have the option of bringing outdoor ferns into the home to overwinter them. To do this, gradually move the plant indoors so it can acclimatize, increasing the hours it spends indoors each day over a number of weeks. You can either bring the plant indoors and position it in bright, indirect light to enjoy it as a houseplant over winter, or you can move it to a dark and cool spot, such as a garage or basement, where it will enter dormancy. When spring rolls around again, you can slowly return the plant to its outside spot.

Humidity

Boston ferns require high levels of humidity, and you will notice the fronds turn brown if this requirement is not met. For indoor ferns, you have a number of options to increase the moisture level of the air. You can use a humidifier, spray the leaves with a water mist, or set the plant on a water pebble tray.

If your Boston fern is kept in a hanging basket to allow the fronds to arch down, a pebble tray will not be possible. Water misting will help to increase humidity, but it is a temporary solution as the water will evaporate so you will need to mist frequently. The drawback of frequent misting is that damp fronds are more susceptible to disease. Using a humidifier is probably the most effective method of increasing humidity for a hanging Boston fern, but those positioned in container pots can benefit from pebble trays (Missouri Botanical Garden).

Propagation

The most common method of propagation for Boston ferns is division. Once your plant reaches a good size, you can remove it from its current pot and divide it into two or more separate plants, repotting back into smaller pots. To do this, you can try to separate the root ball with your fingers to gently tease the roots apart, or you can slice the root ball into sections with a sharp knife. Even a fairly small selection of roots should grow well once transplanted if it is kept in ideal conditions.

Pruning

Nephrolepis exaltata The Sword Fern leaves close up

This plant responds well to trimming and can tolerate severe pruning. Perform an annual reshape or trim in spring when the plant is entering its active growth period, as this is when it will respond best. You can cut your fern right back to the base if you wish to ‘start again,’ or you can prune it to improve the shape or encourage more bushy growth.

Unless you are pruning the whole plant back to the base, don’t cut the top fronds, and instead, trim the fronds from around the edge and underneath. Focus on removing any dead or damaged fronds, and keep as much new growth as possible. If the plant is getting too big or messy looking, trim the tips of the fronds to create a better shape. Aside from the annual pruning, you can remove brown fronds as they appear. It is not uncommon for lower fronds to brown as they are shaded by the new growth. If you have an outdoor Boston fern that you are going to overwinter indoors, it will need to be heavily pruned before it enters dormancy.

Do you have any questions about Boston ferns? Ask in the comments! And please do share this page with other growers.

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Boston Fern Care - Growing Nephrolepis Exaltata

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