Cold hardiness & minimum temperature

Is Motherwort (Leonurus cardiaca)cold hardy? Hardiness zone & min temp

Also called motherwort, throw-wort, lion's ear.

More about motherwort

About Motherwort

Leonurus cardiaca · also called motherwort, throw-wort · herb

Motherwort is a hardy, upright perennial in the mint family with deeply lobed leaves and whorls of small pink-purple flowers prickly with spiny bracts. A traditional medicinal herb for heart and women's complaints, it is tough and undemanding, thriving in sun or part shade on most soils. It self-seeds vigorously and naturalises easily, often behaving like a weed.

Cold limit: USDA 3-8 (cold-hardy perennial) · RHS H7 (-1 to 30°C)

What motherwort's hardiness rating actually means

Yes — motherwort is genuinely cold hardy. Rated RHS H7 and USDA 3-8 (cold-hardy perennial), 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 3-8 (cold-hardy perennial) — 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. Motherwort is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for motherwort 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 motherwort go outside or overwinter — and where?

Plant it out within USDA 3-8 (cold-hardy perennial) 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 motherwort can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Motherwort hardiness — frequently asked questions

Is motherwort cold hardy?

Yes — motherwort is genuinely cold hardy. Rated RHS H7 and USDA 3-8 (cold-hardy perennial), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Motherwort is hardy across USDA 3-8 (cold-hardy perennial); 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 motherwort can survive?

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

What hardiness zone is motherwort?

Motherwort is rated USDA 3-8 (cold-hardy perennial) and RHS H7 — Hardy in the severest European continental winters.

Can motherwort survive winter outside?

Plant it out within USDA 3-8 (cold-hardy perennial) 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 motherwort 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.