Cold hardiness & minimum temperature

Is Crane's Bill Stork's Bill (Erodium gruinum)cold hardy? Hardiness zone & min temp

Also called Crane's Bill Stork's Bill, Iranian Stork's Bill, Long-Beaked Crane's Bill, Grueinum Stork's Bill.

More about crane's bill stork's bill

About Crane's Bill Stork's Bill

Erodium gruinum · also called Crane's Bill Stork's Bill, Iranian Stork's Bill · flowering

Erodium gruinum is a fast-growing annual or biennial native to the eastern Mediterranean and western Asia (Greece, Turkey, Iran), producing upright stems to 40 cm bearing attractive, five-petalled violet-blue flowers with darker veining in summer. Late-summer seedlings will overwinter and flower the following year in mild climates. It self-seeds freely in well-drained, sunny borders and gravel gardens. Not documented as toxic to cats or dogs; classified as mildly-toxic as ASPCA listing for this exact species is unavailable.

Cold limit: USDA 7-10 (annual, self-seeds in zones 6+) · RHS H3 (-5 to 30°C)

Watch for — Damping off in seedlings: Fungal damping off (Pythium, Rhizoctonia) can kill seedlings in cold, wet spring conditions; sow thinly, ensure good drainage, and avoid overwatering at the cotyledon stage.

What crane's bill stork's bill's hardiness rating actually means

Crane's Bill Stork's Bill is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 7-10 (annual, self-seeds in zones 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 about −5 to 1 °C — a light, short frost only. Crane's Bill Stork's Bill shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for crane's bill stork's bill as it gets too cold:

Down to roughly about −5 to 1 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can crane's bill stork's bill go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 7-10 (annual, self-seeds in zones 6+) or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 crane's bill stork's bill can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline crane's bill stork's bill

Crane's Bill Stork'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:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Crane's Bill Stork's Bill hardiness — frequently asked questions

Is crane's bill stork's bill cold hardy?

Crane's Bill Stork's Bill is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 7-10 (annual, self-seeds in zones 6+) (and sheltered UK gardens) crane's bill stork's bill can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature crane's bill stork's bill can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Crane's Bill Stork's Bill shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is crane's bill stork's bill?

Crane's Bill Stork's Bill is rated USDA 7-10 (annual, self-seeds in zones 6+) and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can crane's bill stork's bill survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 7-10 (annual, self-seeds in zones 6+) or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect crane's bill stork's bill from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.