Cold hardiness & minimum temperature

Is Asphodel Cranesbill (Geranium asphodeloides)cold hardy? Hardiness zone & min temp

Also called Asphodel Cranesbill, Starlight Geranium.

More about asphodel cranesbill

About Asphodel Cranesbill

Geranium asphodeloides · also called Asphodel Cranesbill, Starlight Geranium · flowering

Geranium asphodeloides is a leafy perennial native to southern Europe and the Caucasus — from Sicily and Turkey east to the Caucasus and Syria — producing large numbers of delicate pale pink to deep rose flowers with darker veining over a long season from late spring to late summer. It is slightly more tender than most hardy geraniums and benefits from a sheltered position or a dry mulch in colder UK winters. The airy, lax growth habit makes it a graceful companion plant in mixed borders. True Geranium species are non-toxic to cats and dogs per ASPCA guidance.

Cold limit: USDA 5-9 · RHS H5 (-15 to 28°C)

Watch for — Winter crown rot: In heavy wet soils or cold, waterlogged frost pockets, the crown can rot over winter; plant on a raised ridge, mix in grit, and apply a dry mulch of bark or gravel over the crown in November.

What asphodel cranesbill's hardiness rating actually means

Yes — asphodel cranesbill 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. Asphodel Cranesbill is built for winter — once established it takes hard frost and snow in its stride.

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

Asphodel Cranesbill hardiness — frequently asked questions

Is asphodel cranesbill cold hardy?

Yes — asphodel cranesbill 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. Asphodel Cranesbill 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 asphodel cranesbill can survive?

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

What hardiness zone is asphodel cranesbill?

Asphodel Cranesbill is rated USDA 5-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can asphodel cranesbill 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 asphodel cranesbill 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.