Cold hardiness & minimum temperature

Is Ashton's Ice Plant (Delosperma ashtonii)cold hardy? Hardiness zone & min temp

Also called Ashton Delosperma, Ice Plant.

More about ashton's ice plant

About Ashton's Ice Plant

Delosperma ashtonii · also called Ashton Delosperma, Ice Plant · flowering

Delosperma ashtonii is a South African mat-forming succulent producing vivid magenta-purple flowers over a long summer season. It is among the hardier Delosperma species, suited to rock gardens and sunny borders in frost-tolerant climates. Combines well with other alpine and succulent groundcovers. Not individually ASPCA-listed; treat as mildly toxic as a precaution.

Cold limit: USDA 6–10 · RHS H5 (-10–35°C)

Watch for — Winter rot: Waterlogged soil in cold, wet winters is the primary cause of plant loss. Ensure excellent drainage or plant in raised beds.

What ashton's ice plant's hardiness rating actually means

Yes — ashton's ice plant is genuinely cold hardy. Rated RHS H5 and USDA 6–10, 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 6–10 — 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. Ashton's Ice Plant is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for ashton's ice plant 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 ashton's ice plant go outside or overwinter — and where?

Plant it out within USDA 6–10 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 ashton's ice plant can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Ashton's Ice Plant hardiness — frequently asked questions

Is ashton's ice plant cold hardy?

Yes — ashton's ice plant is genuinely cold hardy. Rated RHS H5 and USDA 6–10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Ashton's Ice Plant is hardy across USDA 6–10; 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 ashton's ice plant can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Ashton's Ice Plant is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is ashton's ice plant?

Ashton's Ice Plant is rated USDA 6–10 and RHS H5 — Hardy in most of the UK and in cold winters.

Can ashton's ice plant survive winter outside?

Plant it out within USDA 6–10 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 ashton's ice plant 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.