Cold hardiness & minimum temperature

Is Eryngium bourgatii 'Picos Blue' (Eryngium bourgatii 'Picos Blue')cold hardy? Hardiness zone & min temp

Also called Picos Blue Mediterranean sea holly.

More about eryngium bourgatii 'picos blue'

About Eryngium bourgatii 'Picos Blue'

Eryngium bourgatii 'Picos Blue' · also called Picos Blue Mediterranean sea holly · flowering

'Picos Blue' is a compact Mediterranean sea holly prized for intense violet-blue flower cones and silver-veined, deeply cut basal foliage. A tough, sun-loving, drought-tolerant perennial from Spanish mountain origins, it suits gravel gardens and dry borders. The spiny bracts attract bees and dry beautifully, giving long-lasting summer structure and colour.

Cold limit: USDA 5-9 · RHS H5 (-15 to 30°C)

Watch for — Root and crown rot: Wet or poorly drained soil, particularly in winter, rots the crown. Provide gritty, sharp drainage and keep the base dry.

What eryngium bourgatii 'picos blue''s hardiness rating actually means

Yes — eryngium bourgatii 'picos blue' is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 5-9 — 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 −15 to −10 °C. Eryngium bourgatii 'Picos Blue' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for eryngium bourgatii 'picos blue' as it gets too cold:

It tolerates winter lows to about −15 to −10 °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 eryngium bourgatii 'picos blue' go outside or overwinter — and where?

Plant it out within USDA 5-9 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 eryngium bourgatii 'picos blue' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Eryngium bourgatii 'Picos Blue' hardiness — frequently asked questions

Is eryngium bourgatii 'picos blue' cold hardy?

Yes — eryngium bourgatii 'picos blue' is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Eryngium bourgatii 'Picos Blue' is hardy across USDA 5-9; 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 eryngium bourgatii 'picos blue' can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Eryngium bourgatii 'Picos Blue' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is eryngium bourgatii 'picos blue'?

Eryngium bourgatii 'Picos Blue' is rated USDA 5-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can eryngium bourgatii 'picos blue' survive winter outside?

Plant it out within USDA 5-9 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 eryngium bourgatii 'picos blue' below its minimum temperature?

It tolerates winter lows to about −15 to −10 °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.