Cold hardiness & minimum temperature

Is Overdam Feather Reed Grass (Calamagrostis x acutiflora 'Overdam')cold hardy? Hardiness zone & min temp

Also called Overdam Feather Reed Grass, Variegated Feather Reed Grass, Overdam Reed Grass.

More about overdam feather reed grass

About Overdam Feather Reed Grass

Calamagrostis x acutiflora 'Overdam' · also called Overdam Feather Reed Grass, Variegated Feather Reed Grass · flowering

A variegated form of the Karl Foerster parent, 'Overdam' produces upright clumps of green leaves with bright creamy-white margins that brighten shaded or mixed borders. Golden flower plumes rise above the foliage from early summer, persisting into winter. Sterile (no self-seeding). Adaptable to sun or partial shade with excellent cold hardiness.

Cold limit: USDA 4–8 · RHS H6 (-20 to 32°C)

What overdam feather reed grass's hardiness rating actually means

Yes — overdam feather reed grass 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. Overdam Feather Reed Grass is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for overdam feather reed grass 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 overdam feather reed grass 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 overdam feather reed grass can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Overdam Feather Reed Grass hardiness — frequently asked questions

Is overdam feather reed grass cold hardy?

Yes — overdam feather reed grass 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. Overdam Feather Reed Grass 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 overdam feather reed grass can survive?

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

What hardiness zone is overdam feather reed grass?

Overdam Feather Reed Grass is rated USDA 4–8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can overdam feather reed grass 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 overdam feather reed grass 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.