Cold hardiness & minimum temperature

Is Alpine Heron's Bill (Erodium reichardii)cold hardy? Hardiness zone & min temp

Also called Alpine Heron's Bill, Alpine Geranium, Cranesbill.

More about alpine heron's bill

About Alpine Heron's Bill

Erodium reichardii · also called Alpine Heron's Bill, Alpine Geranium · flowering

Erodium reichardii is a miniature, mat-forming alpine perennial native to rocky limestone slopes in the Balearic Islands and Pyrenees. It bears a long succession of dainty white or pale pink veined flowers from late spring through summer and demands gritty, sharply drained, near-neutral to alkaline soil in a sunny, sheltered position. The single most important care rule is excellent drainage year-round, especially in winter. The genus is not listed as toxic by the ASPCA and is considered low-risk to pets.

Cold limit: USDA 7-10 · RHS H5 (-15 to 25°C)

Watch for — Winter wet rot: Standing moisture in winter causes rapid root and crown rot; prioritise drainage over cold protection — the plant tolerates hard frost far better than wet soil.

What alpine heron's bill's hardiness rating actually means

Yes — alpine heron's bill is genuinely cold hardy. Rated RHS H5 and USDA 7-10, 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 7-10 — 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. Alpine Heron's Bill is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for alpine heron's bill 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 alpine heron's bill go outside or overwinter — and where?

Plant it out within USDA 7-10 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 alpine heron's bill can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Frost protection for borderline alpine heron's bill

Alpine Heron's Bill is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

At the cold edge of its range, mulch the root zone in late autumn to buffer the deepest freezes.
Protect container specimens — pots freeze through far faster than open ground, costing roughly a zone of hardiness.
Shelter new growth from late spring frosts with fleece if a hard night is forecast.

Alpine Heron's Bill hardiness — frequently asked questions

Is alpine heron's bill cold hardy?

Yes — alpine heron's bill is genuinely cold hardy. Rated RHS H5 and USDA 7-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Alpine Heron's Bill is hardy across USDA 7-10; 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 alpine heron's bill can survive?

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

What hardiness zone is alpine heron's bill?

Alpine Heron's Bill is rated USDA 7-10 and RHS H5 — Hardy in most of the UK and in cold winters.

Can alpine heron's bill survive winter outside?

Plant it out within USDA 7-10 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.

How do I protect alpine heron's bill from frost?

At the cold edge of its range, mulch the root zone in late autumn to buffer the deepest freezes. Protect container specimens — pots freeze through far faster than open ground, costing roughly a zone of hardiness. Shelter new growth from late spring frosts with fleece if a hard night is forecast.