Cold hardiness & minimum temperature

Is Shrubby Cone Plant (Conophytum frutescens)cold hardy? Hardiness zone & min temp

Also called Shrubby Cone Plant, Branching Mesemb.

More about shrubby cone plant

About Shrubby Cone Plant

Conophytum frutescens · also called Shrubby Cone Plant, Branching Mesemb · houseplant

Conophytum frutescens is one of the larger Conophytum species, developing short branching stems over time and paired fused leaf bodies. It produces yellow to orange flowers in autumn. More robust than many relatives but still requires strict summer dormancy. Non-toxic and safe around pets.

Cold limit: USDA 9–11 (indoor-only in cool climates) · RHS H2 (5–30°C)

What shrubby cone plant's hardiness rating actually means

Shrubby Cone 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 (indoor-only in cool climates) — 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. Shrubby Cone Plant shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for shrubby cone 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 shrubby cone plant go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9–11 (indoor-only in cool climates) 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 shrubby cone 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 shrubby cone plant

Shrubby Cone 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.

Shrubby Cone Plant hardiness — frequently asked questions

Is shrubby cone plant cold hardy?

Shrubby Cone 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 (indoor-only in cool climates) (and sheltered UK gardens) shrubby cone 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 shrubby cone plant can survive?

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

What hardiness zone is shrubby cone plant?

Shrubby Cone Plant is rated USDA 9–11 (indoor-only in cool climates) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can shrubby cone plant survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9–11 (indoor-only in cool climates) 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 shrubby cone 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.