Cold hardiness & minimum temperature

Is Aizoon Rosularia (Rosularia aizoon)cold hardy? Hardiness zone & min temp

Also called Aizoon Rosularia.

More about aizoon rosularia

About Aizoon Rosularia

Rosularia aizoon · also called Aizoon Rosularia · houseplant

Aizoon Rosularia is a hardy, cushion-forming succulent from rocky mountain habitats in Turkey and the Caucasus. It forms tight mats of small, fleshy rosettes and produces delicate star-shaped flowers in summer. An excellent choice for rock gardens, alpine troughs, or dry sunny windowsills, it demands sharp drainage and minimal water.

Cold limit: USDA 5-9 · RHS H6 (–10–25°C)

Watch for — Crown rot in winter: Wet, cold conditions cause the rosette centre to blacken and collapse. Keep virtually dry from October to February and improve drainage. Remove rotted portions with a clean blade and dust with sulphur powder.

What aizoon rosularia's hardiness rating actually means

Yes — aizoon rosularia is genuinely cold hardy. Rated RHS H6 and USDA 5-9, 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 5-9 — 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 about −20 to −15 °C. Aizoon Rosularia is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for aizoon rosularia 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 aizoon rosularia go outside or overwinter — and where?

Plant it out within USDA 5-9 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 aizoon rosularia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Aizoon Rosularia hardiness — frequently asked questions

Is aizoon rosularia cold hardy?

Yes — aizoon rosularia is genuinely cold hardy. Rated RHS H6 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Aizoon Rosularia is hardy across USDA 5-9; 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 aizoon rosularia can survive?

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

What hardiness zone is aizoon rosularia?

Aizoon Rosularia is rated USDA 5-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can aizoon rosularia survive winter outside?

Plant it out within USDA 5-9 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 aizoon rosularia 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.