Cold hardiness & minimum temperature

Is Valentine's Crown Vetch (Coronilla valentina)cold hardy? Hardiness zone & min temp

Also called Valentine's Crown Vetch, Mediterranean Crown Vetch, Shrubby Scorpion Vetch.

More about valentine's crown vetch

About Valentine's Crown Vetch

Coronilla valentina · also called Valentine's Crown Vetch, Mediterranean Crown Vetch · flowering

Coronilla valentina is a compact, bushy evergreen shrub native to the Mediterranean basin, valued for its clusters of intensely honey-scented bright yellow pea flowers that can appear from late winter through spring and often again in autumn. It thrives in full sun on sharply drained, poor to moderately fertile soils and is one of the more drought-tolerant ornamental shrubs for mild coastal gardens. The most important care fact is that it needs a sheltered, frost-free or lightly frosted position — it is not reliably hardy below about -5 °C (23 °F) and is best grown against a warm, south- or west-facing wall in cooler areas. Coronilla contains coronillin and other glycosides considered toxic to dogs and cats if ingested in quantity.

Cold limit: USDA 8-10 · RHS H3 (-5 to 35 °C)

Watch for — Frost damage in cold winters: Stems and foliage can be killed back in temperatures below -5 °C (23 °F), particularly with cold drying winds. Grow against a warm wall and protect the root zone with a thick mulch in winter; cut damaged stems back to healthy wood in spring.

What valentine's crown vetch's hardiness rating actually means

Valentine's Crown Vetch 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 8-10 — 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 −5 to 1 °C — a light, short frost only. Valentine's Crown Vetch shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for valentine's crown vetch 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 valentine's crown vetch go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-10 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 valentine's crown vetch 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 valentine's crown vetch

Valentine's Crown Vetch 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.

Valentine's Crown Vetch hardiness — frequently asked questions

Is valentine's crown vetch cold hardy?

Valentine's Crown Vetch 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 8-10 (and sheltered UK gardens) valentine's crown vetch can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature valentine's crown vetch can survive?

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

What hardiness zone is valentine's crown vetch?

Valentine's Crown Vetch is rated USDA 8-10 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can valentine's crown vetch survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-10 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 valentine's crown vetch 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.