Cold hardiness & minimum temperature

Is Maughan's Cone Plant (Conophytum maughanii)cold hardy? Hardiness zone & min temp

Also called Maughan's Cone Plant, Pebble Mesemb.

More about maughan's cone plant

About Maughan's Cone Plant

Conophytum maughanii · also called Maughan's Cone Plant, Pebble Mesemb · houseplant

Conophytum maughanii is a choice South African stone succulent forming pairs of small, rounded leaf bodies with fine surface patterning. Autumn brings dainty flowers that open in the afternoon. It demands exceptional drainage, full sun, and a strict summer dry rest. Non-toxic and pet-safe.

Cold limit: USDA 9–11 (indoor-only in cool climates) · RHS H2 (5–28°C)

What maughan's cone plant's hardiness rating actually means

Maughan's 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. Maughan's Cone Plant shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for maughan's 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 maughan's 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 maughan's 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 maughan's cone plant

Maughan's 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.

Maughan's Cone Plant hardiness — frequently asked questions

Is maughan's cone plant cold hardy?

Maughan's 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) maughan's 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 maughan's cone plant can survive?

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

What hardiness zone is maughan's cone plant?

Maughan's 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 maughan's 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 maughan's 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.