Cold hardiness & minimum temperature

Is Winterberry Holly 'Winter Red' (Ilex verticillata 'Winter Red')cold hardy? Hardiness zone & min temp

Also called Winterberry.

More about winterberry holly 'winter red'

About Winterberry Holly 'Winter Red'

Ilex verticillata 'Winter Red' · also called Winterberry · flowering

'Winter Red' is a deciduous winterberry holly that drops its leaves to reveal masses of brilliant red berries persisting into winter, a top choice for wildlife and cut stems. Native to eastern North America, it thrives in moist to wet, acidic soil and full sun, needs a male pollinator like 'Southern Gentleman' to fruit heavily.

Cold limit: USDA 3-9 · RHS H6 (-37 to 30°C)

Watch for — No berries: 'Winter Red' is female and needs a compatible early/mid-season male such as 'Southern Gentleman' within about 15 m to set its heavy fruit display.

What winterberry holly 'winter red''s hardiness rating actually means

Yes — winterberry holly 'winter red' is genuinely cold hardy. Rated RHS H6 and USDA 3-9, 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 3-9 — 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 −20 to −15 °C. Winterberry Holly 'Winter Red' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for winterberry holly 'winter red' 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 winterberry holly 'winter red' 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 winterberry holly 'winter red' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Winterberry Holly 'Winter Red' hardiness — frequently asked questions

Is winterberry holly 'winter red' cold hardy?

Yes — winterberry holly 'winter red' is genuinely cold hardy. Rated RHS H6 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Winterberry Holly 'Winter Red' 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 winterberry holly 'winter red' can survive?

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

What hardiness zone is winterberry holly 'winter red'?

Winterberry Holly 'Winter Red' is rated USDA 3-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can winterberry holly 'winter red' 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 winterberry holly 'winter red' 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.