Cold hardiness & minimum temperature

Is Acorus gramineus 'Variegatus' (Acorus gramineus 'Variegatus')cold hardy? Hardiness zone & min temp

Also called Variegated Japanese Sweet Flag.

More about acorus gramineus 'variegatus'

About Acorus gramineus 'Variegatus'

Acorus gramineus 'Variegatus' · also called Variegated Japanese Sweet Flag · houseplant

Acorus gramineus 'Variegatus' is the cream-and-green striped form of Japanese sweet flag, forming low fans of narrow, aromatic, longitudinally variegated leaves. This slow, semi-evergreen bog perennial brightens pond edges, damp borders and shady containers, and like the species releases a sweet, spicy fragrance when its grassy foliage is bruised.

Cold limit: USDA 5-11 (hardy marginal/bog perennial) · RHS H5 (-15 to 27°C)

What acorus gramineus 'variegatus''s hardiness rating actually means

Yes — acorus gramineus 'variegatus' is genuinely cold hardy. Rated RHS H5 and USDA 5-11 (hardy marginal/bog perennial), it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 5-11 (hardy marginal/bog perennial) — 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 −15 to −10 °C. Acorus gramineus 'Variegatus' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for acorus gramineus 'variegatus' as it gets too cold:

It tolerates winter lows to about −15 to −10 °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 acorus gramineus 'variegatus' go outside or overwinter — and where?

Plant it out within USDA 5-11 (hardy marginal/bog perennial) 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 acorus gramineus 'variegatus' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Acorus gramineus 'Variegatus' hardiness — frequently asked questions

Is acorus gramineus 'variegatus' cold hardy?

Yes — acorus gramineus 'variegatus' is genuinely cold hardy. Rated RHS H5 and USDA 5-11 (hardy marginal/bog perennial), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Acorus gramineus 'Variegatus' is hardy across USDA 5-11 (hardy marginal/bog perennial); 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 acorus gramineus 'variegatus' can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Acorus gramineus 'Variegatus' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is acorus gramineus 'variegatus'?

Acorus gramineus 'Variegatus' is rated USDA 5-11 (hardy marginal/bog perennial) and RHS H5 — Hardy in most of the UK and in cold winters.

Can acorus gramineus 'variegatus' survive winter outside?

Plant it out within USDA 5-11 (hardy marginal/bog perennial) 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 acorus gramineus 'variegatus' below its minimum temperature?

It tolerates winter lows to about −15 to −10 °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.