Cold hardiness & minimum temperature

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

Also called red hot poker, torch lily.

More about kniphofia uvaria

About Kniphofia uvaria

Kniphofia uvaria · also called red hot poker, torch lily · flowering

A dramatic South African perennial forming clumps of arching, grass-like foliage topped by torch-shaped spikes that open red-orange and fade to yellow from summer into autumn, on 0.9-1.2 m stems. It loves full sun and sharp drainage and tolerates drought, coastal sites and poor soil. Pet-safe per the ASPCA, it is a favourite of bees and nectar-feeding birds.

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

Watch for — Crown rot in wet soil: Poor drainage, especially over winter, rots the crown and is the commonest cause of death. Plant on free-draining ground or raised beds, add grit, and avoid mulching directly over the crown.

What kniphofia uvaria's hardiness rating actually means

Yes — kniphofia uvaria 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 uvaria is built for winter — once established it takes hard frost and snow in its stride.

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

Kniphofia uvaria hardiness — frequently asked questions

Is kniphofia uvaria cold hardy?

Yes — kniphofia uvaria 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 uvaria 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 uvaria can survive?

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

What hardiness zone is kniphofia uvaria?

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

Can kniphofia uvaria 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 uvaria 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.