Cold hardiness & minimum temperature

Is Compact Ice Plant (Delosperma congestum)cold hardy? Hardiness zone & min temp

Also called Compact Ice Plant, Gold Nugget Ice Plant, Hardy Ice Plant.

More about compact ice plant

About Compact Ice Plant

Delosperma congestum · also called Compact Ice Plant, Gold Nugget Ice Plant · houseplant

Delosperma congestum is a very cold-hardy, mat-forming Aizoaceae succulent from the Drakensberg mountains of South Africa. It produces abundant bright yellow flowers in summer and is one of the toughest ice plants for temperate gardens. It thrives in full sun with excellent drainage. Not ASPCA-listed; treat cautiously around pets.

Cold limit: USDA 4-9 · RHS H5 (-15 to 30°C)

Watch for — Crown rot in wet winters: Despite its cold hardiness, the crown can rot in waterlogged soil during winter. Ensure excellent drainage, especially in clay-heavy gardens.

What compact ice plant's hardiness rating actually means

Yes — compact ice plant is genuinely cold hardy. Rated RHS H5 and USDA 4-9, 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 4-9 — 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. Compact Ice Plant is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for compact 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 compact ice plant go outside or overwinter — and where?

Plant it out within USDA 4-9 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 compact 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.

Compact Ice Plant hardiness — frequently asked questions

Is compact ice plant cold hardy?

Yes — compact ice plant is genuinely cold hardy. Rated RHS H5 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Compact Ice Plant is hardy across USDA 4-9; 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 compact ice plant can survive?

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

What hardiness zone is compact ice plant?

Compact Ice Plant is rated USDA 4-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can compact ice plant survive winter outside?

Plant it out within USDA 4-9 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 compact 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.