Cold hardiness & minimum temperature

Is Rough Hawk's-beard (Crepis biennis)cold hardy? Hardiness zone & min temp

Also called Rough Hawk's-beard, Biennial Hawk's-beard.

More about rough hawk's-beard

About Rough Hawk's-beard

Crepis biennis · also called Rough Hawk's-beard, Biennial Hawk's-beard · flowering

Rough Hawk's-beard is a biennial native of European meadows, road verges, and rough grassland, naturalised across the UK. In its first year it forms a flat rosette of rough, hispid leaves; in its second year it sends up branched stems to 1.2 m bearing numerous yellow dandelion-like flower heads from May to July, after which it sets seed and dies. The key care fact for wildflower gardens is to allow some plants to set seed each year to maintain continuity, as no plant persists beyond two years. It is considered non-toxic to pets.

Cold limit: USDA 5-9 · RHS H7 (-20 to 30 °C)

What rough hawk's-beard's hardiness rating actually means

Yes — rough hawk's-beard is genuinely cold hardy. Rated RHS H7 and USDA 5-9, 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 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 below about −20 °C. Rough Hawk's-beard is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for rough hawk's-beard 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 rough hawk's-beard 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 rough hawk's-beard can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Rough Hawk's-beard hardiness — frequently asked questions

Is rough hawk's-beard cold hardy?

Yes — rough hawk's-beard is genuinely cold hardy. Rated RHS H7 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Rough Hawk's-beard 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 rough hawk's-beard can survive?

Minimum survivable temperature is roughly below about −20 °C. Rough Hawk's-beard is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is rough hawk's-beard?

Rough Hawk's-beard is rated USDA 5-9 and RHS H7 — Hardy in the severest European continental winters.

Can rough hawk's-beard 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 rough hawk's-beard 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.