Mature size & growth rate

How big does meadow fountain grass (Pennisetum incomptum) get?

Also called meadow fountain grass, restless grass.

More about meadow fountain grass

About meadow fountain grass

Pennisetum incomptum · also called meadow fountain grass, restless grass · flowering

Meadow fountain grass is a vigorous, semievergreen warm-season perennial forming tidy clumps of refined grey-green foliage topped with erect, light-pink to wheat-coloured bottlebrush plumes from midsummer. It withstands heat, drought, and poor soils once established, making it well-suited to sunny borders, meadow plantings, and low-maintenance landscapes.

Mature size: 90–150 cm tall (including flower spikes); spread 60–90 cm

Indoor size vs how big it gets in the wild

meadow fountain 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 90–150 cm tall (including flower spikes). In the ground with no restriction it is a completely different plant — spread 60–90 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

meadow fountain grass is a fast grower. Realistically, expect two to four years from a young plant to a room-filling specimen in good light. Its feeding profile backs this up: generally unnecessary in average soils. if growth is very poor, a single light application of balanced slow-release fertiliser in early spring is sufficient. avoid high-nitrogen feeds, which promote excessive vegetative growth and reduce flowering.

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

How to keep meadow fountain grass smaller

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

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

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

When meadow fountain grass outgrows the room (or the pot)

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

meadow fountain grass size — frequently asked questions

How big does meadow fountain grass get?

meadow fountain grass reaches 90–150 cm tall (including flower spikes) when grown indoors, and far larger where it grows unrestricted (spread 60–90 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 meadow fountain grass slow or fast growing?

meadow fountain grass is a fast grower. Expect two to four years from a young plant to a room-filling specimen in good light. meadow fountain 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 meadow fountain grass take to reach full size?

Roughly two to four years from a young plant to a room-filling specimen in good light. Light, pot size and feeding move that timeline more than anything else.

How do I keep meadow fountain grass smaller?

Divide the clump every year or two — splitting meadow fountain 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 meadow fountain 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.