Everything about Boston Fern

28 Nov 2021

Boston ferns are growing in popularity and there’s plenty of reasons why. Its vibrant, ruffled foliage is a great addition inside the home and outside.

We’re going to explain everything you need to know to grow a thriving Boston fern.

Main Characteristics

Its botanical name is nephrolepis exaltata, however, it is commonly known as Boston fern, sword fern, ladder fern, and boss fern. It is native to South America, Central America, Africa, and Polynesia.

Just like the peace lily, this is also a herbaceous perennial but it belongs to the Nephrolepidaceae family. The best part about this plant is that it remains evergreen throughout the year. Its lush, green droopy fronds are also natural air purifiers.

If you want this fern to flourish, it requires some good care. The Boston fern can be quite temperamental so you’ll need to develop a good care schedule.

Fun Fact: The fern was first discovered in Cambridge, Massachusetts, and then propagated and distributed in the Boston area. This is why it’s commonly known as the Boston fern.

How Big Does It Get?

The Boston fern grows up to 2 to 3 feet wide (61 – 91.5cm) and 1 to 3 feet (30.5 – 91cm) tall if adequately cared for. You can encourage taller and wider growth by planting it outdoors.

How Fast Does It Grow?

Even in optimal conditions, it is a slow-growing plant. The Boston fern is said to grow around 1 inch (2.5cm) taller a year.

How Long Does It Live?

Boston ferns have an incredibly long lifespan! If cared for well, it can live for up to 100 years.

Fun Fact: The oldest Boston fern is 114 years old.

Is It Toxic to Cats, Dogs and Humans?

Fortunately, Boston ferns are non-toxic to cats, dogs, and people. Just like the cat palm, this houseplant is safe to leave around your pets and children.

Boston fern - size, lifespan, toxicity, growth speed (infographics)

Boston Fern Care

As we previously mentioned, this houseplant is finicky. It’s imperative that you create an optimal environment for it and show this plant some love.

How Often to Water It

Keep in mind that this fern is native to tropical regions, so the soil needs to be kept lightly moist, as the fern cannot survive in dry conditions. If you notice that the fronds are becoming dry then you need to water your plant more often.

Typically, the Boston fern needs to be watered 3 – 5 times a week. The fern is sensitive when it comes to watering so you’ll need to develop a regular watering routine.

Top Tip: Use cool or room temperature water when watering the Boston fern to avoid shocking its roots.

Does It Need Drainage?

As the plant requires frequent watering it needs good drainage to prevent a soggy environment. You can ensure that the soil has ingredients promoting drainage to improve it. You can also use a pot with drainage holes to allow excess water to seep out.

How to Trim It

When trimming the sword fern, it is ideal to do so during the early spring. We recommend that you prune it while it is being repotted.

You can prune the houseplant if you’re concerned that its size is becoming unmanageable or to maintain a pristine-looking plant. The fern is very tolerant of heavy pruning, so if you want to cut back a lot of fronds, that’s not a problem.

Follow the steps below:

  1. Sterilize a sharp blade and cut the lower level fronds first.
  2. Pluck off any unhealthy stems as you move up the plant.
  3. Then clip back the outer edges of the houseplant to perfect its shape.


It is best to repot the nephrolepis exaltata during the springtime every 2 to 3 years. You only need to repot it when its roots protrude through the drainage holes, this is known as being pot bound. Additionally, it may be necessary to repot it when it is growing significantly slower.

Follow the step-by-step guide below:

  1. Remove the fern from its current pot and rinse the rootball under a gentle stream of water to get rid of excess soil on the roots.
  2. Find a new pot and fill it with fresh potting soil, then plant the fern.
  3. Make sure that the fern is planted at the same depth and water it well.
  4. Place it back in its original home and care for it as you normally would.


When it comes to the Boston fern it’s important to nail down those basic environmental requirements. It is sensitive to extreme temperatures and it’s finicky about how often it is watered. So, make sure to create a good environment for a thriving plant.

Does It Like Sun?

Nephrolepis exaltata thrives in indirect or partial sunlight just like the sago palm. However, it also needs to be grown in a bright area. You’ll need to find the perfect place where your plant never receives direct sunshine but also isn’t positioned in a shady location.

If your plant is grown in a shady area then its bright, green fronds will eventually begin to fade or lighten in color. When the fronds receive direct light its leaves will become scorched.

Best Soil

The nephrolepis exaltata absolutely loves an acidic, moist potting mixture. Just like the prayer plant, the Boston fern needs to be planted in well-draining soil.

The sword fern also does well in nutrient-rich and loamy soil. The best way to create your own loamy soil is by adding organic matter such as compost or peat moss to an all-purpose general potting mixture.

To improve aeration and drainage, try adding the following ingredients to your potting mixture:

  • Pine bark
  • Vermiculite
  • Sharp sand
  • Gravel


The best type of fertilizer to use is a water-soluble and balanced, liquid fertilizer (20-20-20 or 20-10-20). The fern only requires a light feeding so you should dilute this fertilizer to half its strength. During the summertime, you could also use a slow-releasing fertilizer.

From spring to early autumn you can fertilize it once a month. Once it begins to get colder the plant will enter a state of dormancy so it doesn’t need to be fed between late autumn and winter.

Pot Size and Type

The sword fern requires a little bit of room to grow, so it’s best to plant it in a container that is roughly 2 to 3 inches (5 – 7.5cm) wider than the rootball.

When it comes to the pot’s material, any will do. It should be noted that if you choose to use a terracotta or clay pot then you will have to water your plant more often. Plastic is the best material as it doesn’t absorb water and dry out the soil too much but it allows for water to easily flow out.

Temperature Tolerance

It prospers in temperatures ranging from 60 to 80°F (16 – 26°C). It can withstand temperatures slightly below or above this range. Keep in mind that extreme temperatures can harm this plant, as it will wither away in temperatures below 50°F (10°C) or above 95°F (35°C).

Humidity Level

Humidity is key when it comes to the fern. Nephrolepis exaltata needs to be housed in a humid location. The optimum humidity level is anything above 80 percent. This isn’t common in all homes, however, there are a few ways to increase the humidity level surrounding your plant.

You can place it on top of a tray filled with lukewarm water and gravel. Additionally, you could place other houseplants around the fern or mist its leaves a few times a week.

Top Tip: The easiest way to ensure that your plant is in a humid environment, is by placing a humidifier in the same room as the houseplant.

Can It Live Outside?

The Boston fern is a great option if you want to grow your houseplant outside. It can be grown outdoors year-round and its size actually makes it perfect for the patio.

You should keep in mind that you can only grow it outside throughout the year in USDA hardiness zones of 9 – 11. If you live in a cold region then it’s best to keep the fern indoors as extreme temperatures will cause it to die.

When growing it outdoors, you may have to water it more often as well as place it in a slightly shady area.

Boston fern - care, water, light, pot, temperature, fertilizer (infographics)


The Boston fern does not flower, however, it does begin to form brown spots. Don’t be alarmed as these brown spots are not cause for concern. They are called spores and appear along the edge of a frond.

We’ll explain how to use these spores to propagate a fern later on.

How to Propagate It

You can propagate the fern by dividing its rootball to multiply your collection. Unlike, most houseplants, this fern doesn’t produce seeds, however, you can propagate its spores.

When propagating the houseplant, make sure that the soil is fresh and that your pot is the right size. Additionally, propagation should be done in either spring or summer.

Propagating by Division

Division involves separating the rootball into several sections that can then be planted and grown into a new fern.

  1. First, you’ll need to remove your plant from its container. You can gently slide it out and then brush off any soil around the roots.
  2. Take out a sharp knife and slice a section of the rootball and separate it from the mother plant.
  3. Fill a new pot with soil and plant the division, making sure to cover the roots.
  4. Water the division thoroughly and find a sunny place for it.
  5. Once you tug on the roots and feel resistance, it has successfully rooted.

How to Grow It from Spores

Spores are similar to seeds but they are slower to germinate and grow. You will see smaller black/brown bumps on the lining of the leaves, these are spores. Follow the steps below to successfully grow a new fern from a spore.

  1. Put a piece of paper on a flat surface, then place a frond on it. In the next 3 days, you will notice that tiny spores have fallen on the paper.
  2. Find a shallow tray or container and fill it with a seed-starting mix or some peat moss.
  3. Moisten the potting mixture and then evenly scatter the spores across the soil.
  4. Place a plastic cover over the container to maintain a warm and humid environment. Position the tray in a sunny location.
  5. You may have to wait several months before the spores sprout, and when they do you can remove the plastic.
  6. You only need to repot the plants once they’re big enough.

How to Revive It

In this section, we’re going to describe potential troubles that your plant may experience. We’ll state what to keep your eye out for and how to improve your plant’s health.

Why Is My Plant Turning Brown?

Have you ever noticed that the leaf’s tip, edge, or entire leaf is brown? This is due to improper watering, a lack of moisture, and a fertilizer overdose.

Improper watering is easy to remedy, simply keep the potting mixture moist and monitor the soil by feeling whether it’s dry or not.

If your household’s humidity is low then spritz its leaves with tepid water frequently.

A fertilizer overdose occurs when the plant is fed too much. All you have to do is run a stream of water over the soil for 5 minutes to allow the salts to flush out.

Leaves Falling Off

If you notice that many leaves are consistently dropping off then you are either over- or underwatering the fern. You must never let your potting mixture dry out but your houseplant shouldn’t sit in soggy conditions either.

Leaves Turning Yellow

There are a few culprits causing the yellowing of leaves; cold water, natural aging, a lack of moisture, the pot being too small, and it may be over- or underwatered.

Harsh, cold water can shock the plant’s root system, so it’s best to stick with room temperature water when watering the fern.

Sometimes an older fern naturally loses its yellow leaves. It is completely normal for a few yellow leaves to appear a week, however, anything more than this and you have a problem on your hands.

The fern shouldn’t fit too tightly in its pot. This can cause the plant to become rootbound, therefore, you will need to repot it.

Improper watering is a very common issue. You’ll need to maintain a good watering schedule that keeps the soil moist but not saturated.

Wrapping It Up

The Boston fern is picky when it comes to its environment, so pay special attention to ensure it is placed in a humid environment and watered sufficiently.

By following the various care advice we’ve provided, you should watch your fern grow for many years to come, and maybe it will even survive for a century.

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