Struggling with a Stunted Boston Fern? 6 Potential Causes Holding It Back

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It can be a real bummer when you take good care of a houseplant without seeing any changes on it. No stems growing taller, no leaves flourishing—nothing!

With leafy plants like Boston ferns, growth should be apparent, with leaves getting larger every day. If your Boston fern isn’t growing, something is probably wrong.

So, why is your Boston fern not growing?

Here are all the causes you need to know.

Boston Fern Not Growing – Possible Causes

Boston Ferns refuse to grow when they don’t have enough water, when their soil is compacted and clogged, and when they’re exposed to too much sunlight. Here’s a roundup of the causes.

1 – You’re Not Watering the Plant Enough

Contrary to most houseplants, Boston ferns need plenty of water to grow. They require weekly waterings, and their soil should never dry out. It should always be moist so the plant gets enough nutrients.

If your Boston fern is refusing to grow, there’s a high chance you’re not watering it enough. When the fern’s soil is dry, it’s not getting enough moisture to carry out its daily photosynthesis.

As a result, it’ll stop growing at some point, and the leaves may even start curling or showing yellow edges.

If the weather is too hot, check the soil using your fingers. Dip them in the first 2–3 inches, and see if the soil is dry.

If the plant needs more water, make sure to give it, and adjust the schedule to provide more frequent waterings until the hot temperature subsides.

2 – The Temperature Is Too Low or Too High

Adjusting the temperature for houseplants is one of the most tricky parts of growing them. Any slight difference can cause distress to the plant if it’s lower or higher than the safe range.

For Boston ferns, the optimum range where they can grow and look lively is 65–75 F. The safe range, where they can live without showing signs of distress, is 35–95 F.

Go lower or higher than that, and the plant will start showing yellow leaves and fragile stems.

While the 35–95 range is safe, the plant may not grow if the temperature is higher or lower than the optimum.

Boston ferns don’t take lightly to heat and cold, and they need plenty of humidity to survive.

If the weather is too cold with no humidity, the plant won’t only stop growing, but it’ll start deteriorating as well. So, before exploring the other causes, make sure the ambient temperature is suitable for the plant.

3 – Not Enough Fertilizer

It’s true that Boston ferns can live without fertilizers, but that’s only if the soil conditions are optimal. If the soil is a bit weak, the plant may need a push to grow.

That push often comes in the form of a 20-10-20 fertilizer for houseplants.

During the summer, you can use the fertilizer once a month after diluting it. It’ll give the fern the push it needs, compensating for any nutrients that soil isn’t providing.

Keep from using the fertilizer during the winter; it’s only good for the plant during the summer or spring.

4 – The Air Is Too Dry

Boston ferns thrive in humidity above 80%. That seems like a ridiculously high rate for humans, but without enough moisture, the plant may not grow.

Bear in mind that it originally lives in tropical rainforests, so it’s used to humid air.

If your house is drier than outside, the plant may stop growing, even if it’s getting enough water. The same goes if the plant is placed close to a heating vent or any source of warm drafts.

These may not sound like a big deal, but they can compromise your plant’s growth badly.

You don’t have to keep humidity up to 80% if that’s not applicable in your area; only 50% is enough for the plant to grow. If it’s lower than that, you’ll notice the leaves are not growing.

You can always buy a humidity meter to know for sure, and it wouldn’t hurt to get a humidifier if the air in your house is too dry for the Boston fern.

5 – Your Plant Is Infested by Pests

Like all houseplants, Boston ferns, too, are prone to pest infestation. If spider mites, mealybugs, or even fungus gnats find their way to your plant, chances are, they’ll have a feast on it.

You may not see any changes on the plant, but it’ll stop growing, which is enough reason to worry.

To check for pests, give the Boston fern a thorough inspection. Most pests won’t be visible without a magnifying glass, but there will be some telltale signs.

You’ll see tiny white spots on the leaves, and some leaves will start yellowing. The soil may also have some white wax on it that looks like cotton. That’s usually a sign of mealybugs.

If the plant has a spider-mites infestation, you may see some webbing on the stems.

In all cases, it’d be wise to grab a magnifying glass and check the leaves closely for any signs. The faster you treat the issue, the faster the plant can start growing.

6 – The Fern Is Getting Too Much Sunlight

As I briefly mentioned, Boston ferns originally grow in tropical rainforests. And while these tropical areas get plenty of sunlight, only a few rays manage to reach the ground.

Because of the dense greens, plants don’t receive much sunlight, and that’s how it was intended by nature because these plants only need partial light to grow.

The same goes for Boston ferns. They only need two hours of sunlight daily, and it should be indirect. If you leave them exposed to the sun, their growth will be hindered, and you’ll start seeing signs of stress on their leaves.

Final Thoughts

If you see your Boston fern not growing, there’s no reason to get concerned. You’re likely doing something wrong, and in most cases, it’s easily fixable by reversing the situation.

Always make sure the plant is getting enough water, humidity, and nutrients. It also shouldn’t be left out in the sun.

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