Cold hardiness & minimum temperature

Is Siberian larkspur (Delphinium grandiflorum)cold hardy? Hardiness zone & min temp

Also called Siberian larkspur, Chinese larkspur, Large-flowered delphinium, Butterfly delphinium.

More about siberian larkspur

About Siberian larkspur

Delphinium grandiflorum · also called Siberian larkspur, Chinese larkspur · flowering

A compact, bushy delphinium from Siberia, Mongolia, and China, producing loose clusters of vivid blue, violet, or white flowers on branching stems in early to midsummer. More heat tolerant than the tall elatum hybrids and often treated as a short-lived perennial or annual. Highly toxic to pets and humans. A favourite for cottage borders and cut-flower gardens.

Cold limit: USDA 3-7 · RHS H7 (-35 to 25°C)

What siberian larkspur's hardiness rating actually means

Yes — siberian larkspur is genuinely cold hardy. Rated RHS H7 and USDA 3-7, 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 3-7 — 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. Siberian larkspur is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for siberian larkspur 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 siberian larkspur go outside or overwinter — and where?

Plant it out within USDA 3-7 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 siberian larkspur can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Siberian larkspur hardiness — frequently asked questions

Is siberian larkspur cold hardy?

Yes — siberian larkspur is genuinely cold hardy. Rated RHS H7 and USDA 3-7, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Siberian larkspur is hardy across USDA 3-7; 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 siberian larkspur can survive?

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

What hardiness zone is siberian larkspur?

Siberian larkspur is rated USDA 3-7 and RHS H7 — Hardy in the severest European continental winters.

Can siberian larkspur survive winter outside?

Plant it out within USDA 3-7 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 siberian larkspur 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.