Cold hardiness & minimum temperature

Is Cilician Colchicum (Colchicum cilicicum)cold hardy? Hardiness zone & min temp

Also called Cilician colchicum, Cilician meadow saffron, Autumn crocus.

More about cilician colchicum

About Cilician Colchicum

Colchicum cilicicum · also called Cilician colchicum, Cilician meadow saffron · flowering

Colchicum cilicicum is a vigorous corm-forming perennial from southern Turkey and the Cilicia region, producing large clusters of rosy-pink to magenta, lightly tessellated flowers in autumn, typically September to October, well ahead of the broad, upright leaves that follow in winter. It is one of the most floriferous and garden-worthy colchicums, suited to open borders, gravel gardens, and naturalising under deciduous trees. Provide full sun and excellent drainage, and keep corms dry during summer dormancy. All parts are highly toxic to cats and dogs due to colchicine.

Cold limit: USDA 4-9 · RHS H6 (-15 to 25 °C)

Watch for — Corm rot in waterlogged soil: Persistently wet soil, especially in winter, causes Fusarium and bacterial rot; always plant in sharply drained ground and lift and dry corms if conditions become excessively wet.

What cilician colchicum's hardiness rating actually means

Yes — cilician colchicum is genuinely cold hardy. Rated RHS H6 and USDA 4-9, 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 4-9 — 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 −20 to −15 °C. Cilician Colchicum is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for cilician colchicum 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 cilician colchicum go outside or overwinter — and where?

Plant it out within USDA 4-9 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 cilician colchicum can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Cilician Colchicum hardiness — frequently asked questions

Is cilician colchicum cold hardy?

Yes — cilician colchicum is genuinely cold hardy. Rated RHS H6 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Cilician Colchicum is hardy across USDA 4-9; 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 cilician colchicum can survive?

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

What hardiness zone is cilician colchicum?

Cilician Colchicum is rated USDA 4-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can cilician colchicum survive winter outside?

Plant it out within USDA 4-9 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 cilician colchicum 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.