Cold hardiness & minimum temperature

Is Ribbon Grass (Phalaris arundinacea 'Picta')cold hardy? Hardiness zone & min temp

Also called ribbon grass, gardeners garters, variegated reed canary grass.

More about ribbon grass

About Ribbon Grass

Phalaris arundinacea 'Picta' · also called ribbon grass, gardeners garters · flowering

Ribbon grass, or gardener's garters, is a cool-season variegated grass with bright white-and-green striped blades, sometimes flushed pink in cool weather. Extremely vigorous and rhizomatous, it spreads aggressively and is considered invasive in many regions, so containment is essential. Tough and adaptable, it tolerates sun or shade, wet or dry soil, making it a resilient but assertive groundcover.

Cold limit: USDA 4-9 · RHS H7 (-23 to 29°C)

What ribbon grass's hardiness rating actually means

Yes — ribbon grass 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. Ribbon Grass is built for winter — once established it takes hard frost and snow in its stride.

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

Ribbon Grass hardiness — frequently asked questions

Is ribbon grass cold hardy?

Yes — ribbon grass 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. Ribbon Grass 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 ribbon grass can survive?

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

What hardiness zone is ribbon grass?

Ribbon Grass is rated USDA 4-9 and RHS H7 — Hardy in the severest European continental winters.

Can ribbon grass 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 ribbon grass 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.