Mature size & growth rate

How big does Fishbone Fern (Nephrolepis cordifolia 'Plumosa') get?

Also called Fishbone Fern, Plumosa Fern.

More about fishbone fern

About Fishbone Fern

Nephrolepis cordifolia 'Plumosa' · also called Fishbone Fern, Plumosa Fern · houseplant

Fishbone fern is a tough, upright relative of the Boston fern with narrow, ladder-like fronds whose neat paired leaflets resemble a fishbone. The 'Plumosa' form adds frillier, feathered pinnae. It is one of the most forgiving ferns indoors, tolerating ordinary rooms, and spreads by wiry runners and small tubers, making it easy to share by division.

Mature size: Fronds typically 30-70 cm long; clumps spread steadily by runners to fill a pot or, outdoors, a wide patch.

Indoor size vs how big it gets in the wild

Fishbone 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 clumps spread steadily by runners to fill a pot or, outdoors, a wide patch.. In the ground with no restriction it is a completely different plant — clumps spread steadily by runners to fill a pot or, outdoors, a wide patch. — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

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

Fishbone 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: feed every 4 weeks through spring and summer with a balanced liquid fertiliser at half strength; stop in winter. a vigorous grower, it responds well to regular light feeding but is sensitive to salt buildup, so flush the soil occasionally.

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

How to keep fishbone fern smaller

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

Divide the clump every year or two — splitting fishbone 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 fishbone 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 fishbone fern bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for fishbone 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 fishbone fern light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When fishbone fern outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for fishbone 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 fishbone fern repotting guide. If you want more of this plant instead of a bigger one, the fishbone fern propagation guide turns prunings into new plants.

Fishbone Fern size — frequently asked questions

How big does fishbone fern get?

Fishbone Fern reaches clumps spread steadily by runners to fill a pot or, outdoors, a wide patch. when grown indoors, and far larger where it grows unrestricted (clumps spread steadily by runners to fill a pot or, outdoors, a wide patch.). 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 fishbone fern slow or fast growing?

Fishbone Fern is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Fishbone 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 fishbone 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 fishbone fern smaller?

Divide the clump every year or two — splitting fishbone 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 fishbone 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.