Mature size & growth rate

How big does Garden Catmint (Nepeta x faassenii) get?

Also called garden catmint, Faassen's catmint.

More about garden catmint

About Garden Catmint

Nepeta x faassenii · also called garden catmint, Faassen's catmint · flowering

Garden catmint is a sterile, clump-forming perennial prized for soft grey-green aromatic foliage and long sprays of lavender-blue flowers from late spring into autumn. A magnet for bees and butterflies, it thrives in poor, free-draining soil and full sun, shrugging off heat and drought. Shearing spent flowers triggers a fresh, tidy second flush.

Mature size: 30-45 cm tall and 45-60 cm wide.

Watch for — Flopping after flowering: Stems splay open mid-season, especially in rich soil. Shear the whole plant back by a third to half once the first flush fades to force compact regrowth and a second bloom.

Indoor size vs how big it gets in the wild

Garden Catmint 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 30-45 cm tall and 45-60 cm wide.. 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

Garden Catmint 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: very light feeders. a single spring application of balanced general fertiliser or a thin mulch of compost is ample. over-feeding causes lush, weak growth that flops and flowers poorly.

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

How to keep garden catmint smaller

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

Divide the clump every year or two — splitting garden catmint 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 garden catmint 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 garden catmint bigger or faster

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

When garden catmint outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for garden catmint:

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

Garden Catmint size — frequently asked questions

How big does garden catmint get?

Garden Catmint reaches 30-45 cm tall and 45-60 cm wide. 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 garden catmint slow or fast growing?

Garden Catmint is a fast grower. Expect two to four years from a young plant to a room-filling specimen in good light. Garden Catmint 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 garden catmint 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 garden catmint smaller?

Divide the clump every year or two — splitting garden catmint 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 garden catmint 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.