Mature size & growth rate

How big does Liquorice Blue Korean Mint (Agastache rugosa 'Liquorice Blue') get?

Also called Liquorice Blue Korean Mint, Korean Hyssop, Blue Licorice Mint, Wrinkled Giant Hyssop.

More about liquorice blue korean mint

About Liquorice Blue Korean Mint

Agastache rugosa 'Liquorice Blue' · also called Liquorice Blue Korean Mint, Korean Hyssop · herb

A vigorous, upright perennial herb bearing dense spikes of violet-blue flowers with a strong anise-licorice fragrance. Beloved by bees and butterflies, it thrives in full sun and well-drained soil, tolerates drought once established, and makes a reliable culinary herb for teas, salads, and Asian cooking. Hardy in temperate gardens.

Mature size: 60–90 cm tall, 30–45 cm wide

Watch for — Flopping / legginess: Results from too much shade or overfeeding with nitrogen. Cut back by one-third after the first flush of flowers to encourage compact regrowth and a second bloom.

Indoor size vs how big it gets in the wild

Liquorice Blue Korean Mint 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 60–90 cm tall, 30–45 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

Liquorice Blue Korean Mint 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: apply a balanced, low-nitrogen fertiliser (e.g., 5-10-10) once in early spring. excess nitrogen encourages leafy growth at the expense of flowers. in poor soils, a second light feed in early summer is acceptable.

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

How to keep liquorice blue korean mint smaller

You are not stuck with the maximum size. For liquorice blue korean mint specifically, these are the levers, in order of impact:

Divide the clump every year or two — splitting liquorice blue korean mint 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 liquorice blue korean mint 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 liquorice blue korean mint bigger or faster

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

When liquorice blue korean mint outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for liquorice blue korean mint:

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 liquorice blue korean mint repotting guide. If you want more of this plant instead of a bigger one, the liquorice blue korean mint propagation guide turns prunings into new plants.

Liquorice Blue Korean Mint size — frequently asked questions

How big does liquorice blue korean mint get?

Liquorice Blue Korean Mint reaches 60–90 cm tall, 30–45 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 liquorice blue korean mint slow or fast growing?

Liquorice Blue Korean Mint is a fast grower. Expect two to four years from a young plant to a room-filling specimen in good light. Liquorice Blue Korean Mint 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 liquorice blue korean mint 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 liquorice blue korean mint smaller?

Divide the clump every year or two — splitting liquorice blue korean mint 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 liquorice blue korean mint 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.