Mature size & growth rate

How big does Six Hills Giant Catmint (Nepeta x faassenii 'Six Hills Giant') get?

Also called Six Hills Giant catmint, tall catmint.

More about six hills giant catmint

About Six Hills Giant Catmint

Nepeta x faassenii 'Six Hills Giant' · also called Six Hills Giant catmint, tall catmint · flowering

Six Hills Giant is the tallest, most vigorous garden catmint, sending up arching stems of grey-green foliage smothered in violet-blue flowers from early summer to autumn. Tougher and bigger than common catmint, it makes a billowing front-of-border drift, edges paths and underplants roses. Bees adore it, and shearing after the first flush guarantees a strong rebloom.

Mature size: 75-90 cm tall and 60-90 cm wide.

Indoor size vs how big it gets in the wild

Six Hills Giant 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 75-90 cm tall and 60-90 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

Six Hills Giant 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: a spare feeder. one spring dose of balanced fertiliser or a light compost mulch suffices. rich feeding worsens this cultivar's tendency to grow tall and collapse.

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

How to keep six hills giant catmint smaller

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

Divide the clump every year or two — splitting six hills giant 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 six hills giant 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 six hills giant catmint bigger or faster

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

When six hills giant catmint outgrows the room (or the pot)

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

Six Hills Giant Catmint size — frequently asked questions

How big does six hills giant catmint get?

Six Hills Giant Catmint reaches 75-90 cm tall and 60-90 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 six hills giant catmint slow or fast growing?

Six Hills Giant Catmint is a fast grower. Expect two to four years from a young plant to a room-filling specimen in good light. Six Hills Giant 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 six hills giant 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 six hills giant catmint smaller?

Divide the clump every year or two — splitting six hills giant 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 six hills giant 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.