Cold hardiness & minimum temperature

Is Geranium sylvaticum 'Mayflower' (Geranium sylvaticum 'Mayflower')cold hardy? Hardiness zone & min temp

Also called Mayflower wood cranesbill.

More about geranium sylvaticum 'mayflower'

About Geranium sylvaticum 'Mayflower'

Geranium sylvaticum 'Mayflower' · also called Mayflower wood cranesbill · flowering

'Mayflower' is a selected wood cranesbill prized for its rich violet-blue flowers with small white centres, freely produced in late spring and early summer. An RHS Award of Garden Merit perennial, it forms tidy clumps of lobed foliage, performs in part shade and moist soil, and is among the earliest and most reliable hardy geraniums to bloom.

Cold limit: USDA 3-8 (outdoor perennial) · RHS H7 (-30 to 24°C)

What geranium sylvaticum 'mayflower''s hardiness rating actually means

Yes — geranium sylvaticum 'mayflower' is genuinely cold hardy. Rated RHS H7 and USDA 3-8 (outdoor perennial), 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 3-8 (outdoor perennial) — 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. Geranium sylvaticum 'Mayflower' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for geranium sylvaticum 'mayflower' 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 geranium sylvaticum 'mayflower' go outside or overwinter — and where?

Plant it out within USDA 3-8 (outdoor perennial) 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 geranium sylvaticum 'mayflower' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Geranium sylvaticum 'Mayflower' hardiness — frequently asked questions

Is geranium sylvaticum 'mayflower' cold hardy?

Yes — geranium sylvaticum 'mayflower' is genuinely cold hardy. Rated RHS H7 and USDA 3-8 (outdoor perennial), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Geranium sylvaticum 'Mayflower' is hardy across USDA 3-8 (outdoor perennial); 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 geranium sylvaticum 'mayflower' can survive?

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

What hardiness zone is geranium sylvaticum 'mayflower'?

Geranium sylvaticum 'Mayflower' is rated USDA 3-8 (outdoor perennial) and RHS H7 — Hardy in the severest European continental winters.

Can geranium sylvaticum 'mayflower' survive winter outside?

Plant it out within USDA 3-8 (outdoor perennial) 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 geranium sylvaticum 'mayflower' 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.