Mature size & growth rate

How big does feather grass (Stipa barbata) get?

Also called feather grass, silver feather grass, bearded feather grass.

More about feather grass

About feather grass

Stipa barbata · also called feather grass, silver feather grass · flowering

Feather grass is a graceful short-lived perennial from southern Europe and western Asia, forming dense clumps of slender upright foliage. Its extraordinarily long, silky, silver-white twisted awns — up to 30 cm — dance in the breeze from late spring to early summer, creating a shimmering effect unmatched among ornamental grasses. Thrives in full sun and sharply drained soil.

Mature size: 40–60 cm tall (foliage); flower awns extend to 90 cm; spread 30–60 cm

Indoor size vs how big it gets in the wild

feather grass 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 40–60 cm tall (foliage). In the ground with no restriction it is a completely different plant — flower awns extend to 90 cm; spread 30–60 cm — 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

feather grass 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: no regular fertilisation needed. feeding in fertile soils reduces the tight, ornamental clump habit and can cause the plant to become floppy. in very impoverished soils, a minimal slow-release fertiliser at planting time is the maximum required.

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

How to keep feather grass smaller

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

Divide the clump every year or two — splitting feather grass 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 feather grass 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 feather grass bigger or faster

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

When feather grass outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for feather grass:

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 feather grass repotting guide. If you want more of this plant instead of a bigger one, the feather grass propagation guide turns prunings into new plants.

feather grass size — frequently asked questions

How big does feather grass get?

feather grass reaches 40–60 cm tall (foliage) when grown indoors, and far larger where it grows unrestricted (flower awns extend to 90 cm; spread 30–60 cm). 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 feather grass slow or fast growing?

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

Divide the clump every year or two — splitting feather grass 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 feather grass 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.