Cold hardiness & minimum temperature

Is Geranium x oxonianum (Geranium x oxonianum)cold hardy? Hardiness zone & min temp

Also called Oxford cranesbill, Oxonian geranium.

More about geranium x oxonianum

About Geranium x oxonianum

Geranium x oxonianum · also called Oxford cranesbill, Oxonian geranium · flowering

A vigorous, long-flowering hardy cranesbill, a natural hybrid of G. endressii and G. versicolor that seeds and varies freely. It forms a lush mound of semi-evergreen foliage smothered in pink, dark-veined flowers from late spring through autumn. Tough, shade-tolerant, and near-indestructible, it is one of the best workhorse groundcovers for difficult borders and rough ground.

Cold limit: USDA 4-8 (hardy garden perennial) · RHS H7 (-20 to 27°C)

What geranium x oxonianum's hardiness rating actually means

Yes — geranium x oxonianum is genuinely cold hardy. Rated RHS H7 and USDA 4-8 (hardy garden 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 4-8 (hardy garden 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 x oxonianum is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for geranium x oxonianum 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 x oxonianum go outside or overwinter — and where?

Plant it out within USDA 4-8 (hardy garden 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 x oxonianum can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Geranium x oxonianum hardiness — frequently asked questions

Is geranium x oxonianum cold hardy?

Yes — geranium x oxonianum is genuinely cold hardy. Rated RHS H7 and USDA 4-8 (hardy garden perennial), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Geranium x oxonianum is hardy across USDA 4-8 (hardy garden 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 x oxonianum can survive?

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

What hardiness zone is geranium x oxonianum?

Geranium x oxonianum is rated USDA 4-8 (hardy garden perennial) and RHS H7 — Hardy in the severest European continental winters.

Can geranium x oxonianum survive winter outside?

Plant it out within USDA 4-8 (hardy garden 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 x oxonianum 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.