Mature size & growth rate

How big does Lemon button fern (Nephrolepis cordifolia) get?

Also called fishbone fern, sword fern, erect sword fern.

About Lemon button fern

Nephrolepis cordifolia · also called fishbone fern, sword fern · houseplant

Lemon button fern is a compact upright fern with small round leaflets that smell faintly of lemon when crushed. More forgiving than Boston fern and pet-safe. Tolerates lower humidity than most ferns.

Tuberous sword fern, a pantropical Nephrolepis that is the only sword fern producing small underground tubers; not native to Florida, where UF/IFAS lists it as a FLEPPC Category I invasive that displaces native vegetation.

Spreads by wiry stolons and wind-dispersed spores (year-round in warm climates) to form dense stands; UF/IFAS and FNGA encouraged phasing it out of the nursery trade, so treat it as a contained-pot plant only.

Mature size: 30-45 cm tall

Sources: ask.ifas.ufl.edu, gardeningsolutions.ifas.ufl.edu

Indoor size vs how big it gets in the wild

Lemon button 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 30-45 cm tall. 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

Lemon button 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: half-strength balanced feed monthly in growing season.

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

How to keep lemon button fern smaller

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

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

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

When lemon button fern outgrows the room (or the pot)

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

Lemon button fern size — frequently asked questions

How big does lemon button fern get?

Lemon button fern reaches 30-45 cm tall 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 lemon button fern slow or fast growing?

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

Divide the clump every year or two — splitting lemon button 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 lemon button 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.