Mature size & growth rate

How big does Tufted Hair Grass (Deschampsia cespitosa) get?

Also called tufted hair grass, hassock grass.

More about tufted hair grass

About Tufted Hair Grass

Deschampsia cespitosa · also called tufted hair grass, hassock grass · flowering

Tufted hair grass is a cool-season, clump-forming perennial grass prized for airy, golden flower clouds that hover above dense evergreen mounds of fine arching foliage. Unusually shade-tolerant for an ornamental grass, it thrives in moist, cool, woodland-edge conditions and naturalises in damp meadows. Hardy and low-maintenance, it offers months of soft, translucent inflorescences from early summer.

Mature size: Foliage mound 30-60 cm tall; flowering stems reach 90-120 cm (about 3-4 ft) tall and 60-90 cm wide.

Watch for — Drought browning: Foliage tips and flower stems scorch and brown if the soil dries out; restore even moisture and cut back damaged growth.

Indoor size vs how big it gets in the wild

Tufted Hair 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 foliage mound 30-60 cm tall. In the ground with no restriction it is a completely different plant — flowering stems reach 90-120 cm (about 3-4 ft) tall and 60-90 cm wide. — 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

Tufted Hair 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: undemanding; an annual spring mulch of compost or one light feed of balanced granular fertiliser is ample. avoid high-nitrogen feeds, which cause floppy, lax growth and weaker flowering.

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

How to keep tufted hair grass smaller

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

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

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

When tufted hair grass outgrows the room (or the pot)

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

Tufted Hair Grass size — frequently asked questions

How big does tufted hair grass get?

Tufted Hair Grass reaches foliage mound 30-60 cm tall when grown indoors, and far larger where it grows unrestricted (flowering stems reach 90-120 cm (about 3-4 ft) tall and 60-90 cm wide.). 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 tufted hair grass slow or fast growing?

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

Divide the clump every year or two — splitting tufted hair 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 tufted hair 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.