Cold hardiness & minimum temperature

Is Clubmoss cassiope (Cassiope lycopodioides)cold hardy? Hardiness zone & min temp

Also called Clubmoss cassiope, Lycopodium-like cassiope.

More about clubmoss cassiope

About Clubmoss cassiope

Cassiope lycopodioides · also called Clubmoss cassiope, Lycopodium-like cassiope · flowering

Clubmoss cassiope is a diminutive creeping alpine subshrub native to Japan and the Pacific Northwest, whose overlapping scale-like leaves resemble those of clubmoss. It produces small white nodding bell flowers on slender red stalks in late spring. Best suited to cool, moist, acidic rock gardens or alpine troughs in colder temperate regions.

Cold limit: USDA 3-6 · RHS H7 (−25 to 15°C)

Watch for — Heat stress and summer scorch: This is one of the most demanding Cassiope species regarding cool temperatures. Summer heat above 20°C (68°F) causes browning and dieback. Situate in a cool microclimate, mulch with grit to keep roots cool, and consider an alpine house in warm-summer climates.

What clubmoss cassiope's hardiness rating actually means

Yes — clubmoss cassiope is genuinely cold hardy. Rated RHS H7 and USDA 3-6, 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 3-6 — 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. Clubmoss cassiope is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for clubmoss cassiope 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 clubmoss cassiope go outside or overwinter — and where?

Plant it out within USDA 3-6 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 clubmoss cassiope can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Clubmoss cassiope hardiness — frequently asked questions

Is clubmoss cassiope cold hardy?

Yes — clubmoss cassiope is genuinely cold hardy. Rated RHS H7 and USDA 3-6, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Clubmoss cassiope is hardy across USDA 3-6; 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 clubmoss cassiope can survive?

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

What hardiness zone is clubmoss cassiope?

Clubmoss cassiope is rated USDA 3-6 and RHS H7 — Hardy in the severest European continental winters.

Can clubmoss cassiope survive winter outside?

Plant it out within USDA 3-6 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 clubmoss cassiope 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.