Cold hardiness & minimum temperature

Is Bird-in-a-bush (Corydalis solida)cold hardy? Hardiness zone & min temp

Also called Bird-in-a-bush, Fumewort, Spring Fumitory, Solid-tubered Corydalis.

More about bird-in-a-bush

About Bird-in-a-bush

Corydalis solida · also called Bird-in-a-bush, Fumewort · flowering

Bird-in-a-bush is a tuberous, spring-ephemeral perennial of the poppy family (Papaveraceae) native to Europe and temperate Asia, naturalised in parts of Britain. It emerges from a solid, rounded corm in early spring, producing greyish-green divided leaves and dense racemes of purple-pink spurred flowers before dying down completely by mid-June. The key care point is to plant corms at 5–7 cm depth in humus-rich, well-drained soil in dappled shade and leave them undisturbed once established. Plant material contains alkaloids and is toxic to cats and dogs.

Cold limit: USDA 5-8 · RHS H7 (-25 to 20 °C)

Watch for — Slugs and snails on emerging shoots: The tender young growth emerging in late winter is highly attractive to slugs; apply wildlife-safe iron phosphate pellets or use grit mulch around the crown at first emergence.

What bird-in-a-bush's hardiness rating actually means

Yes — bird-in-a-bush is genuinely cold hardy. Rated RHS H7 and USDA 5-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 5-8 — 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 below about −20 °C. Bird-in-a-bush is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for bird-in-a-bush as it gets too cold:

It tolerates winter lows to about −20 °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 bird-in-a-bush go outside or overwinter — and where?

Plant it out within USDA 5-8 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 bird-in-a-bush can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Bird-in-a-bush hardiness — frequently asked questions

Is bird-in-a-bush cold hardy?

Yes — bird-in-a-bush is genuinely cold hardy. Rated RHS H7 and USDA 5-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Bird-in-a-bush is hardy across USDA 5-8; 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 bird-in-a-bush can survive?

Minimum survivable temperature is roughly below about −20 °C. Bird-in-a-bush is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is bird-in-a-bush?

Bird-in-a-bush is rated USDA 5-8 and RHS H7 — Hardy in the severest European continental winters.

Can bird-in-a-bush survive winter outside?

Plant it out within USDA 5-8 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 bird-in-a-bush below its minimum temperature?

It tolerates winter lows to about −20 °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.