Repotting guide

When & how to repot Liquorice Blue Korean Mint (Agastache rugosa 'Liquorice Blue')

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 — Powdery mildew: Common in humid, poorly ventilated spots. Improve air circulation, avoid overhead watering, and remove affected stems. Resistant cultivars like 'Liquorice Blue' are less susceptible but not immune.

How to tell liquorice blue korean mint needs repotting

Repotting on a calendar is less reliable than reading the plant. For liquorice blue korean mint, watch for these signs:

Roots circling the bottom of the module or pot, or poking out of the drainage holes.
The seedling dries out within a day and growth has visibly stalled.
Roots are white and matted in a tight spiral when you tip the plant out.
It has outgrown its current container for the stage of the season — pot liquorice blue korean mint on before it becomes hard root-bound.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot liquorice blue korean mint

Pot on seedlings as they grow; not a perennial repot. Liquorice Blue Korean Mintis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Clump-forming, upright perennial; self-seeds freely.

What size pot to step liquorice blue korean mint up to

Pot liquorice blue korean mint on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot liquorice blue korean mint

Pot liquorice blue korean mint on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Step-by-step: repotting liquorice blue korean mint

Pot on before it is root-bound. Check liquorice blue korean mint regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
Pot into rich mix. Set it into fresh well-drained loam or sandy loam, ph 6.0–7.5 at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.

Aftercare

Water liquorice blue korean mint in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for liquorice blue korean mint

Liquorice Blue Korean Mint wants well-drained loam or sandy loam, ph 6.0–7.5. Prefers lean to moderately fertile, free-draining soil. Overly rich or waterlogged soil promotes lush but floppy growth and reduces aromatic oil content. Amend clay soils with grit or coarse sand. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting liquorice blue korean mint — frequently asked questions

How often should you repot liquorice blue korean mint?

Pot on seedlings as they grow; not a perennial repot for liquorice blue korean mint. Liquorice Blue Korean Mint is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into well-drained loam or sandy loam, ph 6.0–7.5 so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.

What size pot does liquorice blue korean mint need?

When is the best time of year to repot liquorice blue korean mint?

Can you put liquorice blue korean mint straight into a much bigger pot?

No. Even a fast-growing liquorice blue korean mint should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise liquorice blue korean mint after repotting?

Not immediately. Wait about 1 week after repotting liquorice blue korean mint. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.