Cold hardiness & minimum temperature

Is Cardinal Royal rowan (Sorbus aucuparia 'Cardinal Royal')cold hardy? Hardiness zone & min temp

Also called Cardinal Royal rowan, rowan 'Cardinal Royal', rowan 'Michred'.

More about cardinal royal rowan

About Cardinal Royal rowan

Sorbus aucuparia 'Cardinal Royal' · also called Cardinal Royal rowan, rowan 'Cardinal Royal' · flowering

A tidily columnar rowan bearing prolific clusters of bright blood-red berries from mid-August, more vividly coloured than the native species. Introduced by Michigan State University and sold under the trade name Cardinal Royal ('Michred'), it reaches 8–12 m with a narrow 2.5–4 m spread — ideal for urban streets and small gardens. Fully hardy, RHS H6, pollinator-friendly.

Cold limit: USDA 3-7 · RHS H6 (-20 to 30°C)

Watch for — Aphids (Dysaphis sorbi): Rowan–parsley aphids may cluster on new shoots in spring, causing leaf curl. Natural predator populations usually restore balance by early summer. Apply a winter plant oil wash on dormant stems in persistent cases.

What cardinal royal rowan's hardiness rating actually means

Yes — cardinal royal rowan 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. Cardinal Royal rowan is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for cardinal royal rowan 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 cardinal royal rowan 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 cardinal royal rowan can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Cardinal Royal rowan hardiness — frequently asked questions

Is cardinal royal rowan cold hardy?

Yes — cardinal royal rowan 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. Cardinal Royal rowan 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 cardinal royal rowan can survive?

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

What hardiness zone is cardinal royal rowan?

Cardinal Royal rowan is rated USDA 3-7 and RHS H6 — Hardy throughout the UK and northern Europe.

Can cardinal royal rowan 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 cardinal royal rowan 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.