Cold hardiness & minimum temperature

Is Wherry's Foamflower (Tiarella wherryi)cold hardy? Hardiness zone & min temp

Also called Wherry's foamflower, clump-forming foamflower.

More about wherry's foamflower

About Wherry's Foamflower

Tiarella wherryi · also called Wherry's foamflower, clump-forming foamflower · flowering

Tiarella wherryi is a dainty clump-forming woodland perennial with maple-shaped, often dark-veined leaves and frothy spikes of starry pinkish-white flowers in spring and early summer. Unlike running foamflowers it stays in a tidy mound, making it ideal for shaded borders, woodland edges and ground cover in moist, humus-rich soil under trees and shrubs.

Cold limit: USDA 3-8 (hardy garden perennial) · RHS H7 (-4 to 24°C)

Watch for — Crown rot in wet soil: Heavy, waterlogged ground can rot the crown over winter. Ensure the moisture-retentive soil still drains freely and avoid sitting water around the base.

What wherry's foamflower's hardiness rating actually means

Yes — wherry's foamflower is genuinely cold hardy. Rated RHS H7 and USDA 3-8 (hardy garden perennial), 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 3-8 (hardy garden perennial) — 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. Wherry's Foamflower is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for wherry's foamflower 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 wherry's foamflower go outside or overwinter — and where?

Plant it out within USDA 3-8 (hardy garden perennial) 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 wherry's foamflower can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Wherry's Foamflower hardiness — frequently asked questions

Is wherry's foamflower cold hardy?

Yes — wherry's foamflower is genuinely cold hardy. Rated RHS H7 and USDA 3-8 (hardy garden perennial), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Wherry's Foamflower is hardy across USDA 3-8 (hardy garden perennial); 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 wherry's foamflower can survive?

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

What hardiness zone is wherry's foamflower?

Wherry's Foamflower is rated USDA 3-8 (hardy garden perennial) and RHS H7 — Hardy in the severest European continental winters.

Can wherry's foamflower survive winter outside?

Plant it out within USDA 3-8 (hardy garden perennial) 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 wherry's foamflower 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.