Cold hardiness & minimum temperature

Is Forsythia 'Show Off' (Forsythia × intermedia 'Mindor')cold hardy? Hardiness zone & min temp

Also called Show Off Forsythia.

More about forsythia 'show off'

About Forsythia 'Show Off'

Forsythia × intermedia 'Mindor' · also called Show Off Forsythia · flowering

Forsythia 'Show Off' (cultivar 'Mindor') is a compact, densely branched selection bred for a profusion of deep-yellow flowers packed tightly along short internodes. It blooms more heavily and on a smaller, tidier frame than older forsythias, fitting beds and foundations where 'Lynwood Gold' grows too large, while keeping the same easy, cold-hardy nature.

Cold limit: USDA 5-8 · RHS H6 (-34 to 32°C)

Watch for — Reduced bloom from mistimed pruning: Flowers form on the previous year's wood, so pruning in late summer, autumn, or winter removes next spring's display. Prune only right after flowering and only lightly, given its naturally compact form.

What forsythia 'show off''s hardiness rating actually means

Yes — forsythia 'show off' is genuinely cold hardy. Rated RHS H6 and USDA 5-8, 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 5-8 — 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 about −20 to −15 °C. Forsythia 'Show Off' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for forsythia 'show off' 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 forsythia 'show off' go outside or overwinter — and where?

Plant it out within USDA 5-8 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 forsythia 'show off' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Forsythia 'Show Off' hardiness — frequently asked questions

Is forsythia 'show off' cold hardy?

Yes — forsythia 'show off' is genuinely cold hardy. Rated RHS H6 and USDA 5-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Forsythia 'Show Off' is hardy across USDA 5-8; 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 forsythia 'show off' can survive?

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

What hardiness zone is forsythia 'show off'?

Forsythia 'Show Off' is rated USDA 5-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can forsythia 'show off' survive winter outside?

Plant it out within USDA 5-8 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 forsythia 'show off' 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.