Cold hardiness & minimum temperature

Is Cylindric Arum (Arum cylindraceum)cold hardy? Hardiness zone & min temp

Also called Cylindrical Lords-and-Ladies, Alpine Arum.

More about cylindric arum

About Cylindric Arum

Arum cylindraceum · also called Cylindrical Lords-and-Ladies, Alpine Arum · tropical

Arum cylindraceum is a tuberous perennial aroid native to central and southern Europe into the Caucasus, producing arrow-shaped leaves in spring and a pale spathe with a purple spadix. It dies back in summer after setting vivid red berries. All parts are toxic — the bright berries are especially dangerous to children and pets.

Cold limit: USDA 6-9 · RHS H5 (5-20°C)

Watch for — Failure to flower: Insufficient chilling during winter dormancy; ensure exposure to cool temperatures below 10°C.

What cylindric arum's hardiness rating actually means

Yes — cylindric arum is genuinely cold hardy. Rated RHS H5 and USDA 6-9, 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 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 −15 to −10 °C. Cylindric Arum is built for winter — once established it takes hard frost and snow in its stride.

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

Cylindric Arum hardiness — frequently asked questions

Is cylindric arum cold hardy?

Yes — cylindric arum is genuinely cold hardy. Rated RHS H5 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Cylindric Arum 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 cylindric arum can survive?

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

What hardiness zone is cylindric arum?

Cylindric Arum is rated USDA 6-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can cylindric arum 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 cylindric arum 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.