Cold hardiness & minimum temperature

Is White Wild Quinine (Parthenium integrifolium)cold hardy? Hardiness zone & min temp

Also called wild quinine, American feverfew, eastern feverfew.

More about white wild quinine

About White Wild Quinine

Parthenium integrifolium · also called wild quinine, American feverfew · flowering

A long-blooming eastern North American prairie perennial topped with flat clusters of small chalky-white flowers that resemble cauliflower heads from early summer to autumn. Tough, drought-tolerant, and long-lived, it pairs beautifully with grasses and other natives, draws diverse pollinators, and supplies excellent dried seed heads for winter structure and arrangements.

Cold limit: USDA 4-8 · RHS H6 (-7 to 30°C)

What white wild quinine's hardiness rating actually means

Yes — white wild quinine is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 4-8 — 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 −20 to −15 °C. White Wild Quinine is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for white wild quinine as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 white wild quinine go outside or overwinter — and where?

Plant it out within USDA 4-8 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 white wild quinine can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

White Wild Quinine hardiness — frequently asked questions

Is white wild quinine cold hardy?

Yes — white wild quinine is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. White Wild Quinine is hardy across USDA 4-8; 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 white wild quinine can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. White Wild Quinine is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is white wild quinine?

White Wild Quinine is rated USDA 4-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can white wild quinine survive winter outside?

Plant it out within USDA 4-8 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 white wild quinine below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.