Cold hardiness & minimum temperature

Is Persicaria amplexicaulis 'Blackfield' (Persicaria amplexicaulis 'Blackfield')cold hardy? Hardiness zone & min temp

Also called Blackfield bistort, dark-flowered fleece flower.

More about persicaria amplexicaulis 'blackfield'

About Persicaria amplexicaulis 'Blackfield'

Persicaria amplexicaulis 'Blackfield' · also called Blackfield bistort, dark-flowered fleece flower · flowering

A standout mountain fleece selection with unusually deep crimson-red flower spikes carried over a long season from midsummer to autumn. Its rich, dark blooms rise above robust green foliage on clumps reaching about 1 m. Hardy, moisture-loving and pollinator-rich, 'Blackfield' brings intense late-season colour to borders, bog gardens and naturalistic plantings.

Cold limit: USDA 4-8 · RHS H7 (-20 to 28°C)

What persicaria amplexicaulis 'blackfield''s hardiness rating actually means

Yes — persicaria amplexicaulis 'blackfield' is genuinely cold hardy. Rated RHS H7 and USDA 4-8, 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 4-8 — 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. Persicaria amplexicaulis 'Blackfield' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for persicaria amplexicaulis 'blackfield' 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 persicaria amplexicaulis 'blackfield' go outside or overwinter — and where?

Plant it out within USDA 4-8 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 persicaria amplexicaulis 'blackfield' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Persicaria amplexicaulis 'Blackfield' hardiness — frequently asked questions

Is persicaria amplexicaulis 'blackfield' cold hardy?

Yes — persicaria amplexicaulis 'blackfield' is genuinely cold hardy. Rated RHS H7 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Persicaria amplexicaulis 'Blackfield' is hardy across USDA 4-8; 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 persicaria amplexicaulis 'blackfield' can survive?

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

What hardiness zone is persicaria amplexicaulis 'blackfield'?

Persicaria amplexicaulis 'Blackfield' is rated USDA 4-8 and RHS H7 — Hardy in the severest European continental winters.

Can persicaria amplexicaulis 'blackfield' survive winter outside?

Plant it out within USDA 4-8 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 persicaria amplexicaulis 'blackfield' 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.