Cold hardiness & minimum temperature

Is Caucasian Lily (Lilium monadelphum)cold hardy? Hardiness zone & min temp

Also called Caucasian Lily, Szovits Lily, Yellow Caucasian Lily.

More about caucasian lily

About Caucasian Lily

Lilium monadelphum · also called Caucasian Lily, Szovits Lily · flowering

Lilium monadelphum is a stately, tall true lily from the subalpine meadows and forest margins of the Caucasus and north-eastern Turkey, producing large, fragrant, pendant bells of pale yellow to golden yellow with a delicate speckled interior and reflexed petal tips in early to midsummer. It is notably more tolerant of shade, chalk, and clay than most lilies, making it one of the most garden-worthy and adaptable species for UK conditions. Severely toxic to cats — all Lilium species cause acute renal failure in cats.

Cold limit: USDA 4-8 · RHS H6 (-25°C to 28°C; optimal 12–22°C during growth)

What caucasian lily's hardiness rating actually means

Yes — caucasian lily is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 4-8 — 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 −20 to −15 °C. Caucasian Lily is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for caucasian lily as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 caucasian lily go outside or overwinter — and where?

Plant it out within USDA 4-8 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 caucasian lily can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Caucasian Lily hardiness — frequently asked questions

Is caucasian lily cold hardy?

Yes — caucasian lily is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Caucasian Lily is hardy across USDA 4-8; 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 caucasian lily can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Caucasian Lily is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is caucasian lily?

Caucasian Lily is rated USDA 4-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can caucasian lily survive winter outside?

Plant it out within USDA 4-8 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 caucasian lily below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.