Cold hardiness & minimum temperature

Is Kniphofia triangularis (Kniphofia triangularis)cold hardy? Hardiness zone & min temp

Also called dwarf red hot poker, triangular-leaved torch lily.

More about kniphofia triangularis

About Kniphofia triangularis

Kniphofia triangularis · also called dwarf red hot poker, triangular-leaved torch lily · flowering

Kniphofia triangularis is a compact, hardy South African red hot poker to about 60 cm, forming clumps of slender grassy leaves topped by graceful spikes of pendulous orange to coral-red flowers from late summer into autumn. More cold-tolerant than many torch lilies, it suits sunny, well-drained borders and gravel gardens, and its late blooms are a magnet for bees.

Cold limit: USDA 5-9 · RHS H5 (-23 to 30°C)

Watch for — Winter crown rot: Cold, wet soil rots the crown over winter, the commonest cause of loss. Plant in sharp drainage, keep winter-dry, and tie or fold foliage over the crown to shed water.

What kniphofia triangularis's hardiness rating actually means

Yes — kniphofia triangularis is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 5-9 — 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 −15 to −10 °C. Kniphofia triangularis is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for kniphofia triangularis as it gets too cold:

It tolerates winter lows to about −15 to −10 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can kniphofia triangularis go outside or overwinter — and where?

Plant it out within USDA 5-9 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

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 kniphofia triangularis can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Kniphofia triangularis hardiness — frequently asked questions

Is kniphofia triangularis cold hardy?

Yes — kniphofia triangularis is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Kniphofia triangularis is hardy across USDA 5-9; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature kniphofia triangularis can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Kniphofia triangularis is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is kniphofia triangularis?

Kniphofia triangularis is rated USDA 5-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can kniphofia triangularis survive winter outside?

Plant it out within USDA 5-9 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to kniphofia triangularis below its minimum temperature?

It tolerates winter lows to about −15 to −10 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.