Mature size & growth rate

How big does Bird's Foot Fern (Pellaea mucronata) get?

Also called Bird-Foot Cliffbrake, Mucronate Cliffbrake, Bird Foot Pellaea.

More about bird's foot fern

About Bird's Foot Fern

Pellaea mucronata · also called Bird-Foot Cliffbrake, Mucronate Cliffbrake · houseplant

Pellaea mucronata is a drought-tolerant rock fern native to dry, rocky slopes of the western United States. Its common name refers to the distinctive bird-foot-like arrangement of its small, rounded pinnae on dark wiry stems. Like other Pellaea, it suits bright conditions with infrequent watering. Pet safety is uncertain — treat as mildly toxic.

Mature size: 15-30 cm tall, spreading to 25-35 cm wide

Indoor size vs how big it gets in the wild

Bird's Foot 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 15-30 cm tall, spreading to 25-35 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

Bird's Foot 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 at quarter strength with a balanced liquid fertiliser once every 6-8 weeks in spring and summer only. this fern is adapted to nutrient-poor substrates; excessive fertilising causes weak, flopping growth. flush the pot with plain water periodically.

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

How to keep bird's foot fern smaller

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

Divide the clump every year or two — splitting bird's foot 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 bird's foot 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 bird's foot fern bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for bird's foot fern the accelerators are:

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger.
Good light plus regular feeding maximises offset and runner production.
Leave plantlets and offsets attached and feed through the growing season for the fastest spread.

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

When bird's foot fern outgrows the room (or the pot)

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

Bird's Foot Fern size — frequently asked questions

How big does bird's foot fern get?

Bird's Foot Fern reaches 15-30 cm tall, spreading to 25-35 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 bird's foot fern slow or fast growing?

Bird's Foot Fern is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Bird's Foot 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 bird's foot 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 bird's foot fern smaller?

Divide the clump every year or two — splitting bird's foot 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 bird's foot fern grow bigger or faster?

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger. Good light plus regular feeding maximises offset and runner production. Leave plantlets and offsets attached and feed through the growing season for the fastest spread.