Cold hardiness & minimum temperature

Is Pink Senecio (Senecio glastifolius)cold hardy? Hardiness zone & min temp

Also called Pink senecio, Pink ragwort, Holly-leaved senecio, Woad-leaved ragwort.

More about pink senecio

About Pink Senecio

Senecio glastifolius · also called Pink senecio, Pink ragwort · flowering

Senecio glastifolius is an upright, woody-based perennial herb endemic to the coastal fynbos of the southern Cape Provinces of South Africa, from George to Humansdorp. It bears large, cheerful daisy-like flowers with a single row of lilac-pink to mauve petals around a yellow centre, produced at the tips of branched stems above glossy dark green foliage. In temperate gardens it performs as a half-hardy perennial or short-lived shrub, needing a sunny, sheltered position with well-drained soil and is often grown as an annual in colder climates. Pink senecio contains pyrrolizidine alkaloids characteristic of the Senecio genus and is toxic to dogs and cats.

Cold limit: USDA 9-11 · RHS H2 (0°C to 30°C)

What pink senecio's hardiness rating actually means

Pink Senecio 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. Pink Senecio shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for pink senecio 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 pink senecio 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 pink senecio 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 pink senecio

Pink Senecio 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.

Pink Senecio hardiness — frequently asked questions

Is pink senecio cold hardy?

Pink Senecio 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) pink senecio can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature pink senecio can survive?

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

What hardiness zone is pink senecio?

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

Can pink senecio 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 pink senecio 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.