Cold hardiness & minimum temperature

Is Three-Leaved Stork's Bill (Erodium trifolium)cold hardy? Hardiness zone & min temp

Also called Three-Leaved Stork's Bill, Pelargonium Heron's Bill, Three-Lobed Stork's Bill.

More about three-leaved stork's bill

About Three-Leaved Stork's Bill

Erodium trifolium · also called Three-Leaved Stork's Bill, Pelargonium Heron's Bill · flowering

Erodium trifolium is a clump-forming, short-lived perennial or biennial native to the Atlas Mountains of North Africa, grown for its distinctive felted, three-lobed grey-green leaves and cheerful white to pale pink flowers marked with vivid magenta blotches on the upper petals. It thrives in full sun in gritty, free-draining, neutral to alkaline soil and tolerates drought well once established. The most critical care point is protecting it from excess winter moisture, as prolonged wet conditions will kill the plant even at mild temperatures. Not documented as toxic; classified as mildly-toxic due to limited ASPCA species-level data.

Cold limit: USDA 6-9 · RHS H4 (-10 to 28°C)

Watch for — Crown and root rot: Most commonly fatal issue; triggered by wet winter soils. Plant in raised beds or containers with free-draining alpine compost, and avoid overhead watering in cool weather.

What three-leaved stork's bill's hardiness rating actually means

Yes — three-leaved stork's bill is genuinely cold hardy. Rated RHS H4 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 6-9 — 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 −10 to −5 °C. Three-Leaved Stork's Bill is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for three-leaved stork's bill as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 three-leaved stork's bill go outside or overwinter — and where?

Plant it out within USDA 6-9 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 three-leaved stork's bill can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Three-Leaved Stork's Bill hardiness — frequently asked questions

Is three-leaved stork's bill cold hardy?

Yes — three-leaved stork's bill is genuinely cold hardy. Rated RHS H4 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Three-Leaved Stork's Bill is hardy across USDA 6-9; 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 three-leaved stork's bill can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Three-Leaved Stork's Bill is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is three-leaved stork's bill?

Three-Leaved Stork's Bill is rated USDA 6-9 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can three-leaved stork's bill survive winter outside?

Plant it out within USDA 6-9 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 three-leaved stork's bill below its minimum temperature?

It tolerates winter lows to about −10 to −5 °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.