Cold hardiness & minimum temperature

Is Delphinium 'Pacific Giant' (Delphinium elatum 'Pacific Giant')cold hardy? Hardiness zone & min temp

Also called Larkspur, Candle delphinium.

More about delphinium 'pacific giant'

About Delphinium 'Pacific Giant'

Delphinium elatum 'Pacific Giant' · also called Larkspur, Candle delphinium · flowering

The Pacific Giant strain is the classic tall border delphinium, throwing up dense 1.5-2 m spires packed with large semi-double florets in blues, purples, white and pink, each often with a contrasting 'bee' eye. It demands full sun, deep rich moist soil and staking, and is short-lived. All parts are poisonous.

Cold limit: USDA 3-7 · RHS H7 (10-22°C)

What delphinium 'pacific giant''s hardiness rating actually means

Yes — delphinium 'pacific giant' 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. Delphinium 'Pacific Giant' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for delphinium 'pacific giant' 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 delphinium 'pacific giant' 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 delphinium 'pacific giant' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Delphinium 'Pacific Giant' hardiness — frequently asked questions

Is delphinium 'pacific giant' cold hardy?

Yes — delphinium 'pacific giant' 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. Delphinium 'Pacific Giant' 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 delphinium 'pacific giant' can survive?

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

What hardiness zone is delphinium 'pacific giant'?

Delphinium 'Pacific Giant' is rated USDA 3-7 and RHS H7 — Hardy in the severest European continental winters.

Can delphinium 'pacific giant' 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 delphinium 'pacific giant' 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.