Cold hardiness & minimum temperature

Is Round-leaf Rosularia (Rosularia globulariifolia)cold hardy? Hardiness zone & min temp

Also called Round-leaf Rosularia.

More about round-leaf rosularia

About Round-leaf Rosularia

Rosularia globulariifolia · also called Round-leaf Rosularia · houseplant

A cold-hardy, rosette-forming succulent native to rocky limestone outcrops in southern Turkey and Cyprus. Produces tight rosettes of thick, fleshy, round-tipped leaves and small star-shaped pink or white flowers on erect stems in summer. Exceptionally frost-tolerant for a succulent; excellent for alpine troughs, rock gardens, or cool, bright windowsills.

Cold limit: USDA 5-9 · RHS H5 (-20–35°C)

Watch for — Crown rot in wet winters: The combination of cold and wet soil is the chief killer. In rainy climates, protect with an open cloche or grow under eaves. In pots, move under cover in winter and virtually cease watering.

What round-leaf rosularia's hardiness rating actually means

Yes — round-leaf rosularia is genuinely cold hardy. Rated RHS H5 and USDA 5-9, 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 5-9 — 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 −15 to −10 °C. Round-leaf Rosularia is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for round-leaf rosularia 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 round-leaf 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 round-leaf rosularia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Round-leaf Rosularia hardiness — frequently asked questions

Is round-leaf rosularia cold hardy?

Yes — round-leaf rosularia is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Round-leaf 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 round-leaf rosularia can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Round-leaf Rosularia is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is round-leaf rosularia?

Round-leaf Rosularia is rated USDA 5-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can round-leaf 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 round-leaf rosularia 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.