Cold hardiness & minimum temperature

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

Also called Red Hot Poker, Torch Lily, Tritoma, Poker Plant.

More about red hot poker

About Red Hot Poker

Kniphofia uvaria · also called Red Hot Poker, Torch Lily · flowering

A dramatic South African perennial producing bold, bicoloured torches of tubular flowers — bright red at the top fading to yellow at the base — on tall, upright stems from midsummer to early autumn. The archetypal torch lily, K. uvaria forms substantial clumps of strap-like, evergreen foliage. An outstanding magnet for hummingbirds and bumblebees. Mildly toxic if ingested.

Cold limit: USDA 6-9 · RHS H4 (-10 to 40°C)

Watch for — Crown and rhizome rot: The primary killer, caused by waterlogged soil especially in winter. Plant on slopes, in raised beds, or in soil heavily amended with grit. In cold, wet climates, tie the leaves over the crown in autumn to shed water, or mulch with dry material.

What red hot poker's hardiness rating actually means

Yes — red hot poker is genuinely cold hardy. Rated RHS H4 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 6-9 — 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 −10 to −5 °C. Red Hot Poker is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for red hot poker as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 red hot poker go outside or overwinter — and where?

Plant it out within USDA 6-9 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 red hot poker can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Red Hot Poker hardiness — frequently asked questions

Is red hot poker cold hardy?

Yes — red hot poker is genuinely cold hardy. Rated RHS H4 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Red Hot Poker is hardy across USDA 6-9; 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 red hot poker can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Red Hot Poker is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is red hot poker?

Red Hot Poker is rated USDA 6-9 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can red hot poker survive winter outside?

Plant it out within USDA 6-9 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 red hot poker below its minimum temperature?

It tolerates winter lows to about −10 to −5 °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.