Cold hardiness & minimum temperature

Is Dicliptera suberecta (Dicliptera suberecta)cold hardy? Hardiness zone & min temp

Also called Uruguayan firecracker plant, Hummingbird plant.

More about dicliptera suberecta

About Dicliptera suberecta

Dicliptera suberecta · also called Uruguayan firecracker plant, Hummingbird plant · tropical

Dicliptera suberecta, the Uruguayan firecracker or hummingbird plant, is a South American perennial grown for its velvety, silver-grey woolly foliage and clusters of tubular orange flowers that draw hummingbirds all summer. Forming a low, spreading mound, it is notably drought-tolerant and one of the hardier Acanthaceae, returning from the roots after frost in milder gardens.

Cold limit: USDA 8-11 (root-hardy to about zone 8 with sharp drainage and mulch) · RHS H3 (15-30°C)

Watch for — Crown and root rot: The biggest risk; caused by wet, heavy soil, especially over winter. Plant in sharply drained ground or raised beds and keep dry in the cold season.

What dicliptera suberecta's hardiness rating actually means

Dicliptera suberecta 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 8-11 (root-hardy to about zone 8 with sharp drainage and mulch) — 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. Dicliptera suberecta shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for dicliptera suberecta 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 dicliptera suberecta go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-11 (root-hardy to about zone 8 with sharp drainage and mulch) 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 dicliptera suberecta 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 dicliptera suberecta

Dicliptera suberecta 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.

Dicliptera suberecta hardiness — frequently asked questions

Is dicliptera suberecta cold hardy?

Dicliptera suberecta 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 8-11 (root-hardy to about zone 8 with sharp drainage and mulch) (and sheltered UK gardens) dicliptera suberecta can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature dicliptera suberecta can survive?

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

What hardiness zone is dicliptera suberecta?

Dicliptera suberecta is rated USDA 8-11 (root-hardy to about zone 8 with sharp drainage and mulch) and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can dicliptera suberecta survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-11 (root-hardy to about zone 8 with sharp drainage and mulch) 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 dicliptera suberecta 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.