Cold hardiness & minimum temperature

Is Geranium x oxonianum 'A.T. Johnson' (Geranium x oxonianum 'A.T. Johnson')cold hardy? Hardiness zone & min temp

Also called A.T. Johnson cranesbill, Silver-pink geranium.

More about geranium x oxonianum 'a.t. johnson'

About Geranium x oxonianum 'A.T. Johnson'

Geranium x oxonianum 'A.T. Johnson' · also called A.T. Johnson cranesbill, Silver-pink geranium · flowering

A refined oxonianum cranesbill prized for its abundant silvery-pink, lightly veined flowers carried over a long season from early summer to autumn. 'A.T. Johnson' forms a neat, semi-evergreen mound that works as groundcover or border filler in sun or partial shade. Hardy and easy, it is a softer-coloured, well-behaved alternative to the bolder pink oxonianums.

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

What geranium x oxonianum 'a.t. johnson''s hardiness rating actually means

Yes — geranium x oxonianum 'a.t. johnson' 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 'A.T. Johnson' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for geranium x oxonianum 'a.t. johnson' 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 'a.t. johnson' 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 'a.t. johnson' 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 'A.T. Johnson' hardiness — frequently asked questions

Is geranium x oxonianum 'a.t. johnson' cold hardy?

Yes — geranium x oxonianum 'a.t. johnson' 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 'A.T. Johnson' 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 'a.t. johnson' can survive?

Minimum survivable temperature is roughly below about −20 °C. Geranium x oxonianum 'A.T. Johnson' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is geranium x oxonianum 'a.t. johnson'?

Geranium x oxonianum 'A.T. Johnson' is rated USDA 4-8 (hardy garden perennial) and RHS H7 — Hardy in the severest European continental winters.

Can geranium x oxonianum 'a.t. johnson' 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 'a.t. johnson' 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.