Mature size & growth rate

How big does Fishtail Sword Fern (Nephrolepis falcata) get?

Also called Fishtail Sword Fern, Fishtail Fern, Sickle-leaved Sword Fern.

More about fishtail sword fern

About Fishtail Sword Fern

Nephrolepis falcata · also called Fishtail Sword Fern, Fishtail Fern · houseplant

Nephrolepis falcata is a distinctive tropical sword fern recognisable by its uniquely forked or fish-tail-shaped pinnae, unlike the simple pinnae of other Nephrolepis. Native to Southeast Asia and Pacific Islands, it brings bold, architectural texture to interiors and patios. Relatively easy to grow with moderate watering and humidity. Non-toxic to pets.

Mature size: 60–100 cm tall, 60–90 cm wide

Watch for — Loss of forked pinnae character: Under low-light or nutrient-poor conditions, new fronds may produce less pronounced forking and appear closer to a standard sword fern. Ensure adequate bright indirect light, feed regularly during growth, and the distinctive fishtail form will reassert itself on new fronds.

Indoor size vs how big it gets in the wild

Fishtail Sword Fern stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward. Indoors and in a pot, expect 60–100 cm tall, 60–90 cm wide. A pot, your light levels and a little pruning are what set the final size in a home, far more than the plant's theoretical potential.

Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Growth rate and years to mature

Fishtail Sword Fern is a moderate grower. Realistically, expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Its feeding profile backs this up: apply a balanced liquid fertiliser at half strength every 4 weeks during spring and summer. avoid heavy feeding, which can cause soft, susceptible growth and brown leaf tips from salt accumulation. do not fertilise in autumn or winter when growth naturally slows.

Want this turned into the right next pot at the right moment? The pot size calculator and the fishtail sword fern repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast fishtail sword fern grows.

How to keep fishtail sword fern smaller

You are not stuck with the maximum size. For fishtail sword fern specifically, these are the levers, in order of impact:

Divide the clump every year or two — splitting fishtail sword fern is the main way to control its spread and refresh it.
Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump.
Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

The keep-it-smaller method, step by step

Lift the whole plant. Slide fishtail sword fern out of its pot in spring when the clump has filled it.
Split the clump. Tease or cut the rootball into two or more sections, each with healthy roots and growth.
Repot one division. Put a single division back in the original pot to reset it to a smaller size; pot or give away the rest.
Remove offsets as they form. Through the year, detach new runners or pups to stop it spreading again.

How to grow fishtail sword fern bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for fishtail sword fern the accelerators are:

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger.
Brighter light speeds up clump and offset production noticeably.
Leave plantlets and offsets attached and feed through the growing season for the fastest spread.

Light is almost always the ceiling. The fishtail sword fern light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When fishtail sword fern outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for fishtail sword fern:

The clump bulging over the pot rim or splitting the pot — the cue to divide, not to find a bigger room.
A dense centre that goes bare or tired while the edges keep spreading.
Runners or offsets escaping across the shelf or into neighbouring pots.

If it is the pot rather than the room, it is a repotting job, not a goodbye — see the fishtail sword fern repotting guide. If you want more of this plant instead of a bigger one, the fishtail sword fern propagation guide turns prunings into new plants.

Fishtail Sword Fern size — frequently asked questions

How big does fishtail sword fern get?

Fishtail Sword Fern reaches 60–100 cm tall, 60–90 cm wide when grown indoors. Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Is fishtail sword fern slow or fast growing?

Fishtail Sword Fern is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Fishtail Sword Fern stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward.

How long does fishtail sword fern take to reach full size?

Roughly three to six years to reach mature indoor size, gaining a steady amount each growing season. Light, pot size and feeding move that timeline more than anything else.

How do I keep fishtail sword fern smaller?

Divide the clump every year or two — splitting fishtail sword fern is the main way to control its spread and refresh it. Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump. Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

How can I make fishtail sword fern grow bigger or faster?

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger. Brighter light speeds up clump and offset production noticeably. Leave plantlets and offsets attached and feed through the growing season for the fastest spread.