Mature size & growth rate

How big does Crocodile fern (Microsorum musifolium) get?

Also called alligator fern, crocodile leaf fern.

About Crocodile fern

Microsorum musifolium · also called alligator fern, crocodile leaf fern · houseplant

Crocodile fern is a tropical Asian fern with broad strap leaves marked with a striking dark crocodile-skin pattern. Pet-safe and prefers high humidity. Easier than maidenhair fern but still needs consistent moisture.

Microsorum musifolium, an epiphytic fern native from southern Myanmar through Indonesia, Borneo and New Guinea, growing on rainforest tree trunks and branches, not in ground soil.

Erect, arching habit roughly 30-90cm tall and wide, with broad strap-like fronds whose puckered network of darker veins gives the crocodile-skin look; best propagated by spring division.

Mature size: 60-90 cm tall and wide

Sources: plants.ces.ncsu.edu, missouribotanicalgarden.org

Indoor size vs how big it gets in the wild

Crocodile 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 60-90 cm tall and 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

Crocodile 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: quarter-strength balanced feed every 4-6 weeks in growing season.

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

How to keep crocodile fern smaller

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

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

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

When crocodile fern outgrows the room (or the pot)

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

Crocodile fern size — frequently asked questions

How big does crocodile fern get?

Crocodile fern reaches 60-90 cm tall and 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 crocodile fern slow or fast growing?

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

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