Cold hardiness & minimum temperature

Is Liquorice Blue Korean Mint (Agastache rugosa 'Liquorice Blue')cold hardy? Hardiness zone & min temp

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.

Cold limit: USDA 5–9 · RHS H5 (−15°C to 35°C)

What liquorice blue korean mint's hardiness rating actually means

Yes — liquorice blue korean mint is genuinely cold hardy. Rated RHS H5 and USDA 5–9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 5–9 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about −15 to −10 °C. Liquorice Blue Korean Mint is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for liquorice blue korean mint as it gets too cold:

It tolerates winter lows to about −15 to −10 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can liquorice blue korean mint go outside or overwinter — and where?

Plant it out within USDA 5–9 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when liquorice blue korean mint can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Liquorice Blue Korean Mint hardiness — frequently asked questions

Is liquorice blue korean mint cold hardy?

Yes — liquorice blue korean mint is genuinely cold hardy. Rated RHS H5 and USDA 5–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Liquorice Blue Korean Mint is hardy across USDA 5–9; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature liquorice blue korean mint can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Liquorice Blue Korean Mint is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is liquorice blue korean mint?

Liquorice Blue Korean Mint is rated USDA 5–9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can liquorice blue korean mint survive winter outside?

Plant it out within USDA 5–9 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to liquorice blue korean mint below its minimum temperature?

It tolerates winter lows to about −15 to −10 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.