How to care for a Boston fern | Nephrolepis exaltata

If there’s any plant that’s perfect to bring that forest feel into your home, it’s ferns. Some ferns can be quite a challenge to keep alive (maidenhair fern, anyone?), but luckily there are also species that don’t require extremely green thumbs. Nephrolepis exaltata, also known as the Boston fern, is an amazingly lush houseplant that you’ll love to have in your home.

Keep reading for everything you need to know about how to care for a Boston fern!

Name(s) (Common, scientific)Boston fern, sword fern, Nephrolepis exaltata
Difficulty levelIntermediate
LightBright indirect
WaterKeep lightly moist
SoilSomewhat water-retaining

Boston fern natural habitat

Boston ferns are understory plants with a large natural range: they’re endemic to South America, Mexico, the Caribbean, Florida, Africa and Polynesia. Here, like most other ferns, they grow in shaded and moist areas.

Given that they are found in tropical areas, Boston ferns’ ideal conditions are not always met at home. Luckily though, their general hardiness helps them survive and thrive nonetheless. 

Did you know? Although Boston ferns in the home are pretty much always grown terrestrially (in soil), they can also be epiphytes in the wild. This means they grow on trees in a non-parasitic manner.

White wall with hanging houseplants including spider plant and Boston fern | Full guide on caring for a Boston fern

Boston fern light and temperature

Light

Since Boston ferns naturally grow beneath other plants, they thrive best in bright, indirect light. Direct sun is just too harsh for their thin, papery fronds. They’ll do well in north-facing windows (in the Northern Hemisphere) where the most intense rays of the sun won’t reach them. If direct sun does come in through the window, try protecting the plant with a sheer curtain.

If you decide to grow your Boston ferns outdoors for part or all of the year, make sure that they are near other plants or objects to help filter any harsh sunlight.

Did you know? It’s okay to keep this species outside in many areas. Boston ferns can actually survive light frost. However, they’ll die off when exposed to too much cold, so you might want to avoid it if you don’t want to have to look at an empty planter for a while.

Temperature

Boston ferns are tropical plants, so they like heat and humidity. Temperature-wise, you should aim to keep them between 50-70 degrees Fahrenheit (10-21 degrees Celsius). If you are feeling nice and cozy in your home, chances are your ferns are, too!

When it comes to humidity, Boston ferns aren’t as needy as other ferns. However, that doesn’t mean they don’t still like higher than average humidity levels. Over 80% is ideal, which is a lot higher than the average in most homes. Definitely keep yours away from heater and air conditioning units to avoid yellow leaves.

Making a special home for your Boston fern in your bathroom or kitchen can help, provided that it still receives enough light there. Other ways that you can help with humidity include using a humidifier, pebble tray, or keeping a bunch of tropical plants together.

Did you know? You can mist your Boston fern’s leaves if you want, although this doesn’t help the plant for long. In fact, the positive effects on humidity tend to disappear in as little as 15 minutes. However, misting the plants can help in other ways, such as keeping some pests at bay (spider mites hate humidity, for example).

Fronds of a Boston fern, Nephrolepis exaltata

Boston fern soil and planting

Soil

Caring for Boston ferns when it comes to soil is similar to caring for a lot of other houseplants. Boston ferns do well with acidic soil rich in organic matter. It should be able to retain a lot of water without becoming too soggy. The plant likes moisture, after all, but it doesn’t like standing water. The excess should be able to drain.

As usual, choosing or making mixes with perlite and coco coir can help with drainage. The former is the draining element while the latter retains water to ensure things don’t go too dry.

Planting

Boston ferns like fresh soil. This, paired with the fact that they can grow quite large, means you’ll probably end up having to repot every spring.

If you don’t want to move your Boston fern to a larger container every year, there’s two things you can do. Our personal favorite option is of course to divide it so that you end up with two smaller plants. Scroll down to the section on propagation for more information on that.

Alternatively, you could simply prune the root ball. The plant will be cranky about that for a bit but it should bounce back just fine.

Tip: As with other houseplants, you Boston fern’s container should always have a drainage hole. A simple plastic nursery planter works well, since the plastic material helps retain water. Many houseplant enthusiasts also like using hanging planters for this species.

Curly Boston fern houseplant.
It might not look much like your average Boston fern, but it still is one! There are actually many curly cultivars of this fern species out there.

Watering Boston fern

When it comes to Boston fern care, the number one question is often how much do you need to water. Unfortunately, we can’t give you an exact watering schedule. It depends on light, temperature, soil type, the size of your plant and more.

You have to learn to figure out when the plant needs moisture. The best way to get a feel for it is to just check the soil very regularly. If the top inch or two is dry, it’s time to refill that watering can. A bit more in summer when new fronds are popping up left, right and center, a bit less in winter when the plant is dormant.

Most people find themselves watering Boston ferns once every 7 to 10 days, though your mileage may vary.

Tip: Since Boston ferns can grow a bit out of control, it may be hard to see or touch the soil. In this case, you can do the pot test: all you need to do is lift the plant. As you become more familiar with your plant, you’ll know how heavy it is when it’s first watered and how light it becomes when it’s drying out. Once you feel the pot being lighter than usual, you can water.

Boston fern fertilizer

When caring for Boston ferns, you can use a general liquid fertilizer diluted to half or quarter strength during the growing season, once or twice a month as needed.

They really don’t need much, though, especially if you tend to repot into fresh soil on a yearly basis.

Mini Nephrolepis exaltata houseplant | Guide on caring for a Boston fern

Propagating Boston fern

Propagating Boston ferns is really easy, which is great for people who want more of them to love. Basically, there are two methods for propagating Boston ferns. The most common and easier method is to divide the mother plant.

Since Boston ferns grow so big and lush, it’s easy to cut your chosen plant into fourths or even eighths and repot. Once you’ve noticed your plant becoming compact or root bound in its pot, just let the soil dry out a bit, then use a sterilized knife to cut through the roots. After you divide the plant, simply repot the new sections in fresh soil and you’re good to go!

The second, less common method is to snip off the runners that Boston ferns send out. You can then repot the new plants and watch them grow.

In both cases, it’s best to propagate and repot during spring and summer, which is the growing season. You may also want to consider repotting in plastic or ceramic pots to better retain moisture. As always, just make sure that the pots still have good drainage.

Nephrolepis exaltata houseplant in terrarium | Guide on caring for a Boston fern
An old fish bowl makes a fine container for a Boston fern and keeps the humidity in.

Problems with Boston fern

It’s important to remember that when caring for Boston ferns, some amount of die-off is natural. For instance, if some of the lower fronds begin yellowing and falling off, there’s nothing to worry about. You might also find fallen leaves around the plant on a regular basis.

Pruning away these dead fronds should just be part of your everyday Boston fern care routine. You may also notice leaves dropping if you’ve just made a sudden change, such as moving the plant inside from outdoors.

However, if the leaves start noticeably drooping, that’s when you should start troubleshooting. Unfortunately, drooping or yellowing can indicate a number of different issues (such as too little light or overwatering) and it’s difficult to figure out which is the exact culprit. Additionally, yellow, crunchy tips can indicate that the air is too dry or the tap water is too hard.

If any of the above issues occur, the best thing you can do is to review all elements of your Boston fern care and see where it might be lacking. Did it go from summer to winter but did you fail to reduce watering? Have you started turning on the air-con, causing the air humidity to drop?

When it comes to pests, Boston ferns can be affected by all the usual houseplant pests, such as mealybugs, so you’ll have to keep an eye out. Check new plants before you add them to the rest of your collection.

Buying Boston fern

Since caring for Boston ferns is so easy, and the plant is such a stunner, you can easily find them in nurseries or online.

When shopping, keep in mind that the plants may not look exactly like you expect them to. There are loads of Boston fern cultivars out there with different sizes and leaf shapes.

Tip: Are you a fern enthusiast? Don’t forget to check out a bunch of other fern favorites in the article on easy ferns.

Is Boston fern toxic to cats and dogs?

Pet lovers can rest easy knowing that, according to the ASPCA, Boston ferns are non-toxic to cats and dogs!

However, as always, you should still make sure to keep the plants out of reach of any curious critters. All plants cause a slight upset stomach and your fern definitely won’t appreciate being munched on either.


If you have any more questions about how to care for a Boston fern or want to share your own experiences with these lush houseplants, don’t hesitate to leave a comment below! 🌱