Mature size & growth rate

How big does Pony Tails Grass (Stipa tenuissima) get?

Also called ponytails grass, fine-leaved tussock grass.

More about pony tails grass

About Pony Tails Grass

Stipa tenuissima · also called ponytails grass, fine-leaved tussock grass · flowering

Stipa tenuissima (now Nassella tenuissima) is a soft, fine-textured ornamental grass forming feathery tussocks that ripple in the slightest breeze. Bright green spring foliage matures to buff with silky flower plumes. It thrives in full sun and sharp drainage, is very drought-tolerant, and self-seeds freely, which can become invasive in mild climates.

Mature size: Typically 40-60 cm tall and wide, the flower plumes adding a little height above the foliage.

Indoor size vs how big it gets in the wild

Pony Tails 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 typically 40-60 cm tall and wide, the flower plumes adding a little height above the foliage.. 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

Pony Tails 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: needs no feeding on most soils and is best kept lean. feeding produces floppy, short-lived growth. omit fertiliser entirely except as a token spring dose on truly impoverished ground.

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

How to keep pony tails grass smaller

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

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

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

When pony tails grass outgrows the room (or the pot)

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

Pony Tails Grass size — frequently asked questions

How big does pony tails grass get?

Pony Tails Grass reaches typically 40-60 cm tall and wide, the flower plumes adding a little height above the foliage. 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 pony tails grass slow or fast growing?

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

Divide the clump every year or two — splitting pony tails 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 pony tails 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.