Cold hardiness & minimum temperature

Is Silvery Yarrow (Achillea clavennae)cold hardy? Hardiness zone & min temp

Also called Silvery Yarrow, Clavenna's Yarrow, White Yarrow.

More about silvery yarrow

About Silvery Yarrow

Achillea clavennae · also called Silvery Yarrow, Clavenna's Yarrow · flowering

Achillea clavennae is a low-growing alpine yarrow from the limestone mountains of central and southern Europe, forming silvery-white, finely dissected foliage mats topped with small white daisy-like flowerheads from early to midsummer. Extremely drought and heat tolerant once established, it is ideal for dry rock gardens, gravel gardens, and sunny alpine troughs.

Cold limit: USDA 3–9 · RHS H7 (-20–30°C)

Watch for — Root rot in wet or heavy soil: The number one cause of death in cultivation. Achillea clavennae cannot tolerate waterlogged or poorly drained soil, especially in winter. Plant in raised beds or troughs with gritty, lean soil, and avoid overwatering at all times. Winter wet is far more damaging than frost.

What silvery yarrow's hardiness rating actually means

Yes — silvery yarrow is genuinely cold hardy. Rated RHS H7 and USDA 3–9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 3–9 — 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 below about −20 °C. Silvery Yarrow is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for silvery yarrow as it gets too cold:

It tolerates winter lows to about −20 °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 silvery yarrow go outside or overwinter — and where?

Plant it out within USDA 3–9 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 silvery yarrow can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Silvery Yarrow hardiness — frequently asked questions

Is silvery yarrow cold hardy?

Yes — silvery yarrow is genuinely cold hardy. Rated RHS H7 and USDA 3–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Silvery Yarrow is hardy across USDA 3–9; 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 silvery yarrow can survive?

Minimum survivable temperature is roughly below about −20 °C. Silvery Yarrow is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is silvery yarrow?

Silvery Yarrow is rated USDA 3–9 and RHS H7 — Hardy in the severest European continental winters.

Can silvery yarrow survive winter outside?

Plant it out within USDA 3–9 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 silvery yarrow below its minimum temperature?

It tolerates winter lows to about −20 °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.