Cold hardiness & minimum temperature

Is Harlequin Flower (Sparaxis tricolor)cold hardy? Hardiness zone & min temp

Also called Harlequin flower, Wand flower, Three-coloured sparaxis.

More about harlequin flower

About Harlequin Flower

Sparaxis tricolor · also called Harlequin flower, Wand flower · flowering

Sparaxis tricolor is a cormous perennial native to the Western Cape of South Africa, producing cheerful funnel-shaped blooms in red, orange, or purple with a vivid yellow throat ringed in black during spring. It thrives in full sun and sharply drained, sandy soil, and must be kept completely dry during its summer dormancy or the corms will rot. In the UK and cooler US climates it is best grown under glass in autumn-planted pots and kept frost-free; in USDA zones 9–10 it naturalises freely in the ground. It is considered mildly toxic to pets and should be kept out of reach of cats and dogs.

Cold limit: USDA 9-11 (lift and store in zones 7-8) · RHS H2 (5–25°C)

What harlequin flower's hardiness rating actually means

Harlequin Flower 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 (lift and store in zones 7-8) — 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. Harlequin Flower shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for harlequin flower 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 harlequin flower go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (lift and store in zones 7-8) 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 harlequin flower 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 harlequin flower

Harlequin Flower 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.

Harlequin Flower hardiness — frequently asked questions

Is harlequin flower cold hardy?

Harlequin Flower 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 (lift and store in zones 7-8) (and sheltered UK gardens) harlequin flower can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature harlequin flower can survive?

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

What hardiness zone is harlequin flower?

Harlequin Flower is rated USDA 9-11 (lift and store in zones 7-8) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can harlequin flower survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (lift and store in zones 7-8) 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 harlequin flower 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.