Cold hardiness & minimum temperature

Is Corn Mint (Mentha arvensis)cold hardy? Hardiness zone & min temp

Also called Corn Mint, Wild Mint, Field Mint, Japanese Mint.

More about corn mint

About Corn Mint

Mentha arvensis · also called Corn Mint, Wild Mint · herb

Corn Mint is a vigorous, rhizomatous perennial native to moist fields and hedgerows across Eurasia and North America. It produces whorls of pale lilac flowers on leafy stems and is the primary commercial source of natural menthol. Grow in moist soil with partial shade and contain roots to prevent spreading.

Cold limit: USDA 4-9 · RHS H7 (10–24°C)

What corn mint's hardiness rating actually means

Yes — corn mint is genuinely cold hardy. Rated RHS H7 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 4-9 — 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 below about −20 °C. Corn Mint is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for corn mint as it gets too cold:

It tolerates winter lows to about −20 °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 corn mint go outside or overwinter — and where?

Plant it out within USDA 4-9 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 corn mint can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Corn Mint hardiness — frequently asked questions

Is corn mint cold hardy?

Yes — corn mint is genuinely cold hardy. Rated RHS H7 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Corn Mint is hardy across USDA 4-9; 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 corn mint can survive?

Minimum survivable temperature is roughly below about −20 °C. Corn Mint is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is corn mint?

Corn Mint is rated USDA 4-9 and RHS H7 — Hardy in the severest European continental winters.

Can corn mint survive winter outside?

Plant it out within USDA 4-9 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 corn mint below its minimum temperature?

It tolerates winter lows to about −20 °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.