Cold hardiness & minimum temperature

Is Marson's Crown Cactus (Rebutia marsoneri)cold hardy? Hardiness zone & min temp

Also called Marson's Rebutia, Yellow Crown Cactus, Crown Cactus.

More about marson's crown cactus

About Marson's Crown Cactus

Rebutia marsoneri · also called Marson's Rebutia, Yellow Crown Cactus · houseplant

Rebutia marsoneri is a classic, freely flowering cactus from Argentina producing masses of bright yellow to orange flowers from the base in spring. It is robust, offsetting readily to form dense clumps and tolerating cooler temperatures that suit a bright, unheated windowsill. Not listed as toxic by the ASPCA.

Cold limit: USDA 9-10 · RHS H3 (5-30°C)

Watch for — Overwatering rot: Most common in autumn and winter. Ensure long dry-down periods between waterings as temperatures cool.

What marson's crown cactus's hardiness rating actually means

Marson's Crown Cactus is half-hardy (RHS H3). 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 H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 9-10 — 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 −5 to 1 °C — a light, short frost only. Marson's Crown Cactus shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for marson's crown cactus as it gets too cold:

Down to roughly about −5 to 1 °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 marson's crown cactus go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-10 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 marson's crown cactus can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline marson's crown cactus

Marson's Crown Cactus 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.

Marson's Crown Cactus hardiness — frequently asked questions

Is marson's crown cactus cold hardy?

Marson's Crown Cactus is half-hardy (RHS H3). 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 9-10 (and sheltered UK gardens) marson's crown cactus can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature marson's crown cactus can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Marson's Crown Cactus shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is marson's crown cactus?

Marson's Crown Cactus is rated USDA 9-10 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can marson's crown cactus survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-10 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 marson's crown cactus 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.