Cold hardiness & minimum temperature

Is Big Bluestem (Andropogon gerardii)cold hardy? Hardiness zone & min temp

Also called big bluestem, turkey foot grass, beard grass.

More about big bluestem

About Big Bluestem

Andropogon gerardii · also called big bluestem, turkey foot grass · flowering

Big bluestem is the iconic tall-grass prairie dominant of North America, reaching 1.5–2 m with striking blue-green foliage that turns fiery copper-red and burgundy in autumn. Its distinctive three-pronged seed heads — earning the name 'turkey foot' — persist through winter. Deeply drought-tolerant and wildlife-valuable, it is a foundation species of native and prairie-style gardens.

Cold limit: USDA 4–9 · RHS H7 (−34°C to 40°C)

Watch for — Slow to emerge in spring: As a warm-season grass, big bluestem does not break dormancy until soil temperatures reliably exceed 15°C. Apparent 'deadness' in early spring is normal — delay cutting back dead foliage until late winter to provide winter wildlife habitat, then cut to 10 cm before new growth appears.

What big bluestem's hardiness rating actually means

Yes — big bluestem 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. Big Bluestem is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for big bluestem 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 big bluestem 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 big bluestem can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Big Bluestem hardiness — frequently asked questions

Is big bluestem cold hardy?

Yes — big bluestem 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. Big Bluestem 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 big bluestem can survive?

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

What hardiness zone is big bluestem?

Big Bluestem is rated USDA 4–9 and RHS H7 — Hardy in the severest European continental winters.

Can big bluestem 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 big bluestem 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.