Mature size & growth rate

How big does bluejoint reedgrass (Calamagrostis canadensis) get?

Also called bluejoint reedgrass, bluejoint, Canadian reedgrass.

More about bluejoint reedgrass

About bluejoint reedgrass

Calamagrostis canadensis · also called bluejoint reedgrass, bluejoint · flowering

Bluejoint reedgrass is a vigorous native North American cool-season grass thriving in wet meadows, marshes, and streambanks. It forms dense stands of upright, arching stems topped with purple-tinged panicles in early summer that fade to tawny gold. Excellent for naturalising wet and boggy areas, it provides important wildlife and waterfowl habitat and erosion control along watercourses.

Mature size: 90-150 cm tall and spreading indefinitely via rhizomes in suitable moist conditions.

Watch for — Aggressive spreading: In moist, fertile conditions bluejoint spreads vigorously by rhizomes and can become invasive in small gardens; site only where spread is acceptable or install root barriers.

Indoor size vs how big it gets in the wild

bluejoint reedgrass 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 and spreading indefinitely via rhizomes in suitable moist conditions.. 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

bluejoint reedgrass 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 requires no feeding in its preferred wet, fertile conditions. in garden settings a single light spring compost mulch is sufficient. avoid fertilising established stands in naturalistic or wildlife areas.

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

How to keep bluejoint reedgrass smaller

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

Divide the clump every year or two — splitting bluejoint reedgrass 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 bluejoint reedgrass 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 bluejoint reedgrass bigger or faster

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

When bluejoint reedgrass outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for bluejoint reedgrass:

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

bluejoint reedgrass size — frequently asked questions

How big does bluejoint reedgrass get?

bluejoint reedgrass reaches 90-150 cm tall and spreading indefinitely via rhizomes in suitable moist conditions. 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 bluejoint reedgrass slow or fast growing?

bluejoint reedgrass is a fast grower. Expect two to four years from a young plant to a room-filling specimen in good light. bluejoint reedgrass 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 bluejoint reedgrass 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 bluejoint reedgrass smaller?

Divide the clump every year or two — splitting bluejoint reedgrass 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 bluejoint reedgrass 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.