Mature size & growth rate

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

Also called Garden Catmint, Blue Catmint, Faassen's Catnip.

More about garden catmint

About Garden Catmint

Nepeta × faassenii · also called Garden Catmint, Blue Catmint · herb

Garden Catmint is a mounding, aromatic perennial prized for its lavender-blue flower spikes and silver-green foliage. A sterile hybrid, it blooms prolifically from late spring to autumn if cut back after the first flush. Drought-tolerant and deer-resistant, it thrives at border edges in full sun.

Mature size: 30–45 cm tall (12–18 in), 45–60 cm wide (18–24 in)

Watch for — Flopping after first bloom: Cut plants back by half immediately after the first flowering flush (typically early summer) to encourage a compact second flush of bloom and tidy growth.

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 (12–18 in), 45–60 cm wide (18–24 in). 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 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: rarely needed in the ground. a light top-dressing of balanced granular fertiliser in early spring suffices. over-feeding produces lush, floppy growth at the expense of flowers. container-grown plants benefit from a low-nitrogen liquid feed monthly.

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 (12–18 in), 45–60 cm wide (18–24 in) 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 moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. 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 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 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.