Cold hardiness & minimum temperature

Is Coreopsis 'Sienna Sunset' (Coreopsis 'Sienna Sunset')cold hardy? Hardiness zone & min temp

Also called Sienna Sunset Tickseed, Warm Shades Coreopsis.

More about coreopsis 'sienna sunset'

About Coreopsis 'Sienna Sunset'

Coreopsis 'Sienna Sunset' · also called Sienna Sunset Tickseed, Warm Shades Coreopsis · flowering

Coreopsis 'Sienna Sunset' is a warm-toned perennial tickseed bearing single daisy flowers in rich blends of orange, copper, and sienna-red from summer into autumn. It forms a neat, compact clump and is heat- and drought-tolerant once established in full sun and well-drained soil. Coreopsis is non-toxic to pets per the ASPCA.

Cold limit: USDA 4-9 · RHS H6 (-15-32°C)

Watch for — Colour fading in heat: Very high summer temperatures can bleach the warm sienna tones. In hot climates, light afternoon shade may preserve flower colour.

What coreopsis 'sienna sunset''s hardiness rating actually means

Yes — coreopsis 'sienna sunset' is genuinely cold hardy. Rated RHS H6 and USDA 4-9, 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 4-9 — 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. Coreopsis 'Sienna Sunset' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for coreopsis 'sienna sunset' 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 coreopsis 'sienna sunset' go outside or overwinter — and where?

Plant it out within USDA 4-9 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 coreopsis 'sienna sunset' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Coreopsis 'Sienna Sunset' hardiness — frequently asked questions

Is coreopsis 'sienna sunset' cold hardy?

Yes — coreopsis 'sienna sunset' is genuinely cold hardy. Rated RHS H6 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Coreopsis 'Sienna Sunset' is hardy across USDA 4-9; 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 coreopsis 'sienna sunset' can survive?

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

What hardiness zone is coreopsis 'sienna sunset'?

Coreopsis 'Sienna Sunset' is rated USDA 4-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can coreopsis 'sienna sunset' survive winter outside?

Plant it out within USDA 4-9 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 coreopsis 'sienna sunset' 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.