Cold hardiness & minimum temperature

Is Caucasian Draba (Draba bruniifolia)cold hardy? Hardiness zone & min temp

Also called Caucasian Draba, Mossy Draba, Brunnifolia Whitlow Grass.

More about caucasian draba

About Caucasian Draba

Draba bruniifolia · also called Caucasian Draba, Mossy Draba · flowering

Draba bruniifolia is a tiny, bun-forming evergreen perennial from the Caucasus and adjacent mountains of Turkey and Iran, growing in rocky scree and crevices at subalpine to alpine elevations. It forms dense mounds of deep green, softly hairy rosettes and bears clusters of bright yellow flowers in early spring, making it one of the most reliably floriferous small drabas in cultivation. Perfect drainage and full sun are essential; it performs best in cool-summer climates, making it well suited to UK troughs and alpine beds. Toxicity data are absent from the ASPCA database; classified as mildly-toxic as a precautionary measure.

Cold limit: USDA 4-9 · RHS H5 (-25 to 20°C)

Watch for — Crown and root rot: Wet, poorly drained soil — especially over winter — rapidly kills the central rosette; plant in a raised scree bed or vertical rock crevice and mulch the crown with fine grit.

What caucasian draba's hardiness rating actually means

Yes — caucasian draba is genuinely cold hardy. Rated RHS H5 and USDA 4-9, 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 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 −15 to −10 °C. Caucasian Draba is built for winter — once established it takes hard frost and snow in its stride.

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

Caucasian Draba hardiness — frequently asked questions

Is caucasian draba cold hardy?

Yes — caucasian draba is genuinely cold hardy. Rated RHS H5 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Caucasian Draba 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 caucasian draba can survive?

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

What hardiness zone is caucasian draba?

Caucasian Draba is rated USDA 4-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can caucasian draba 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 caucasian draba 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.