Cold hardiness & minimum temperature

Is Trailing Ice Plant (Lampranthus spectabilis)cold hardy? Hardiness zone & min temp

Also called Trailing ice plant, Shining mesembryanthemum, Ice plant.

More about trailing ice plant

About Trailing Ice Plant

Lampranthus spectabilis · also called Trailing ice plant, Shining mesembryanthemum · flowering

Lampranthus spectabilis is a trailing succulent perennial native to the Western Cape of South Africa, where it grows on dry, rocky hillsides in full sun. It needs sharply drained, lean soil and minimal water once established, producing a dazzling flush of daisy-like flowers in magenta, purple, or pink in late winter through spring. The single most important care fact is that overwatering is the principal cause of failure — the roots will rot in any soil that stays moist. According to the ASPCA, Lampranthus (ice plant) is non-toxic to cats and dogs.

Cold limit: USDA 9-11 · RHS H2 (7–35°C)

What trailing ice plant's hardiness rating actually means

Trailing Ice Plant is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 9-11 — 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 1 to 5 °C — tolerates cold but no real frost. Trailing Ice Plant shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for trailing ice plant as it gets too cold:

Down to roughly about 1 to 5 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can trailing ice plant go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 trailing ice plant can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline trailing ice plant

Trailing Ice Plant is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Trailing Ice Plant hardiness — frequently asked questions

Is trailing ice plant cold hardy?

Trailing Ice Plant is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 9-11 (and sheltered UK gardens) trailing ice plant can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature trailing ice plant can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Trailing Ice Plant shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is trailing ice plant?

Trailing Ice Plant is rated USDA 9-11 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can trailing ice plant survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect trailing ice plant from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.