Cold hardiness & minimum temperature

Is Sensation Mix Cosmos (Cosmos bipinnatus)cold hardy? Hardiness zone & min temp

Also called Garden Cosmos, Mexican Aster, Sensation Cosmos.

More about sensation mix cosmos

About Sensation Mix Cosmos

Cosmos bipinnatus · also called Garden Cosmos, Mexican Aster · flowering

A tall, airy annual with feathery foliage and large bowl-shaped flowers in shades of pink, crimson, and white, reaching 90–120 cm. Sensation Mix is a classic cut-flower series, extremely easy to grow in full sun. Not listed as toxic by ASPCA; considered non-toxic to dogs and cats.

Cold limit: USDA Annual in all zones (zones 2–11 as summer annual) · RHS H1C (frost-tender annual) (16–32°C)

What sensation mix cosmos's hardiness rating actually means

Yes — sensation mix cosmos is genuinely cold hardy. Rated RHS H7 and USDA Annual in all zones (zones 2–11 as summer annual), 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 Annual in all zones (zones 2–11 as summer annual) — 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. Sensation Mix Cosmos is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for sensation mix cosmos 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 sensation mix cosmos go outside or overwinter — and where?

Plant it out within USDA Annual in all zones (zones 2–11 as summer annual) 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 sensation mix cosmos can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Sensation Mix Cosmos hardiness — frequently asked questions

Is sensation mix cosmos cold hardy?

Yes — sensation mix cosmos is genuinely cold hardy. Rated RHS H7 and USDA Annual in all zones (zones 2–11 as summer annual), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Sensation Mix Cosmos is hardy across USDA Annual in all zones (zones 2–11 as summer annual); 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 sensation mix cosmos can survive?

Minimum survivable temperature is roughly below about −20 °C. Sensation Mix Cosmos is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is sensation mix cosmos?

Sensation Mix Cosmos is rated USDA Annual in all zones (zones 2–11 as summer annual) and RHS H7 — Hardy in the severest European continental winters.

Can sensation mix cosmos survive winter outside?

Plant it out within USDA Annual in all zones (zones 2–11 as summer annual) 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 sensation mix cosmos 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.