Cold hardiness & minimum temperature

Is Woolly yarrow (Achillea tomentosa)cold hardy? Hardiness zone & min temp

Also called Woolly yarrow, Yellow wooly yarrow.

More about woolly yarrow

About Woolly yarrow

Achillea tomentosa · also called Woolly yarrow, Yellow wooly yarrow · flowering

A low-growing, mat-forming yarrow prized for its dense, soft grey-green woolly foliage and cheerful yellow flower heads held above the carpet on short stems. Superb for the front of sunny borders, rock gardens, dry slopes, and paving crevices. Extremely drought-tolerant and heat-resistant once established, it withstands light foot traffic and suppresses weeds effectively.

Cold limit: USDA 3–7 · RHS H6 (-25 to 38°C)

Watch for — Crown rot in winter wet: The chief risk for this species is sitting in cold, wet soil over winter. Plant on a slope or raised bed, improve drainage with coarse grit, and avoid mulching directly over the crown.

What woolly yarrow's hardiness rating actually means

Yes — woolly yarrow is genuinely cold hardy. Rated RHS H6 and USDA 3–7, 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 3–7 — 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. Woolly yarrow is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for woolly yarrow 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 woolly yarrow go outside or overwinter — and where?

Plant it out within USDA 3–7 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 woolly yarrow can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Woolly yarrow hardiness — frequently asked questions

Is woolly yarrow cold hardy?

Yes — woolly yarrow is genuinely cold hardy. Rated RHS H6 and USDA 3–7, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Woolly yarrow is hardy across USDA 3–7; 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 woolly yarrow can survive?

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

What hardiness zone is woolly yarrow?

Woolly yarrow is rated USDA 3–7 and RHS H6 — Hardy throughout the UK and northern Europe.

Can woolly yarrow survive winter outside?

Plant it out within USDA 3–7 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 woolly yarrow 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.