Growing Guides

Boston Fern

(Nephrolepis exaltataBostoniensis‘)

The Boston Fern I have indoors is adorably tiny and relatively unchanging. It’s still the same width as when I salvaged it from the clearance section of a store last year – though much more green and full of foliage. This fern has been just about the easiest plant in my collection to take care of; the same effort as cacti, though you trade more water for less spikes. It’s a worthwhile trade.

When I first hung it at home, I wasn’t quite sure how to take care of it. The dirt and sphagnum moss the wall-mounted planter had come with were quite dry. Most plants can agree that dry soil is not conducive to strong growth. I soaked the whole pot in water until I was sure it was wet, then replaced the moss on top with some fresher stuff. A few fronds had to be trimmed, and some dry leaves fell off on their own. That’s been about the extent of the drama in regards to my Boston Fern.

Seriously- if you’re looking for a low-stress plant that does quite well in somewhat dim light, this plant is a dream.


Characteristics

As far as plants go, ferns are old-fashioned. They don’t flower, and they don’t produce seeds. Instead, these big bundles of leaves (fronds) develop spores on their undersides. They haven’t changed much in hundreds of millions of years, so the conditions they’re used to may not be exactly like the inside of your home. Still, they’re durable, cheerfully green, and pretty low-maintenance. There’s a few legends as to why this particular species was called a Boston fern – the predominant being simply that a botanist in Massachusetts got some of these in a shipment and helped make them wildly popular.

The Boston Fern can grow as high as 7 feet in its natural habitat, though the ‘Bostoniensis‘ cultivar is not quite so far-reaching. It has a little higher tolerance for light and dryness than other species might enjoy. You can leave it alone more than other ferns, without worrying as much. There have been weeks lately where I simply didn’t find the time to water mine on the proper schedule, and only a single frond would start to yellow. They’re really quite peaceable.

The shape and style of this fern lend it the classification of ‘sword fern’, though these are much softer than a real sword.

Origin

Tropical regions of the Americas, Africa, and Polynesia

Care

Water

High humidity is this plant’s happy place. During the winter, even your indoor air will likely be a tad too dry. Try misting the plant once or twice a week, or keeping it around many other plants so they can share in the transpiration. It likes 50% (or even 80%) humidity if it can get it, so the 10-15% of most homes will be too low. It’ll survive… but adding some humidity will help it thrive.

The soil should remain moist. Check the soil very often – nearly daily – to make sure it’s moist. I add a layer of sphagnum moss over the dirt to help retain moisture. It’s a good idea to soak the fern’s soil once a month or so, then let it drain properly. After weeks of adding a bit of water at a time, the soil can compact or form channels that the water passes through – soaking helps to properly hydrate all corners of the soil.

When the plant goes dormant in the winter, you can reduce the watering quite heavily. It won’t need much water again until it wakes back up.

Light

When indoors, it prefers bright indirect light. When outdoors, it’ll like heavily shaded or dappled lighting. This is not a full-sun plant! Mine do not get direct light at any point, but are a few feet to the side of the window.

When the plant goes dormant in the winter, the plant can be overwintered in a dark place, such as a basement. This is a good way to keep it from suffering especially cold winters.

Temperature

This plant is happiest around room temperature. Keep it in a spot that’s between 60 and 75 degrees if possible – not any warmer or colder. My indoor ferns have survived much higher temperature (indoors in LA during the summer…), though they generally aren’t happy about it.

Boston Ferns may hibernate during the cool winter. Store at a temp above 55 degrees to overwinter. The plant can only survive temperatures below 50 degrees for a short while.

It’s possible to overwinter the plant outside in zones 8b-11. Some of the nearby outdoors ferns here are growing year-round in a place that’s zone 10b or so, alongside the building.

Fertilizer

They do not need much fertilizer. Only fertilize sparingly, a few times throughout the year if you feel the need. When you propagate these plants by division, the new soil you put it in will likely contain adequate amounts of nutrients.

The Dirt

Soil

Moist, well-draining, humus-y soil. Slightly acidic, ph of 5 to 5.5. I add a layer of sphagnum moss over the soil to retain moisture.

Root & Pot

This plant thrives in small to medium pots. Larger pots should be terracotta or something porous to help the soil breathe, or in a shape that allows the soil to breathe some. Keep an eye on smaller terracotta pots, as the soil may dry out quite quickly. My indoor ferns are quite happy in 4″ plastic pots when indoors.

Even if this plant hasn’t quite outgrown its pot, it needs to be repotted every spring. The stems can overcrowd the plant, leading to wilting leaves and eventually a dead plant. Give it a chance to move around. When repotting in the spring, this is a good chance to divide the plant and add to the collection.

Size & Speed

The exaltata species can grow up to 7 feet in its natural habitat, so the ‘Bostoniensis‘ cultivar is a much more comfortable version to grow at home. It’ll reach 2 or 3 feet tall at the largest, though they can be kept quite a bit smaller.

Occasionally remove dead fronds and rotate the plant so it’ll develop evenly. If you’re keeping a potted Boston Fern outdoors and plan to bring it inside for winter, this is a good time to prune away all but the healthiest fronds.

Later Life

Propagation

Propagates via spore or division. Spores are the fern equivalent of the flower/seed process, and comes with its own difficulties. Much easier is propagating via division – splitting up the plant into separate whole chunks, each containing viable fronds and roots. When repotting in the spring, make sure each of the divisions has a good chunk of roots available to it. Easy peasy.

Flower & Fruit

Doesn’t flower or produce fruit.

Edibility

Supposedly, you can eat the tuber (thick root section) that grows below-ground. It contains quite a bit of water. I haven’t tried one personally, so I can’t recommend this one way or the other. Please consult further research and your own conscience before eating a strange plant.

Problems

Pests & Diseases

Spider mites and mealybugs.

Trouble Signs

The leaves will turn yellow if the humidity is not high enough.

Other Notes

Non-toxic to dogs and cats, though I’m not sure they’d much want to eat it.

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A boston fern in a wall-mounted wooden planter

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