Cold hardiness & minimum temperature

Is Mexican Fleabane (Erigeron karvinskianus)cold hardy? Hardiness zone & min temp

Also called Mexican Fleabane, Santa Barbara Daisy, Karwinski's Fleabane, Profusion Daisy.

More about mexican fleabane

About Mexican Fleabane

Erigeron karvinskianus · also called Mexican Fleabane, Santa Barbara Daisy · flowering

Mexican Fleabane is a sprawling, semi-evergreen perennial producing an endless succession of small white-to-pink daisy flowers from late spring through autumn. A prolific self-seeder, it naturalises beautifully in wall crevices, paving gaps, and rockeries. Tough and drought-tolerant once established, it requires minimal care beyond occasional trimming to prevent it smothering neighbours.

Cold limit: USDA 5–9 · RHS H4 (-10 to 30°C)

Watch for — Frost damage to foliage: In colder zones (5–6) the semi-evergreen foliage may be cut back by hard frost. Plants typically regenerate strongly from the base in spring; cut back damaged growth in early spring.

What mexican fleabane's hardiness rating actually means

Yes — mexican fleabane is genuinely cold hardy. Rated RHS H4 and USDA 5–9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 5–9 — 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 −10 to −5 °C. Mexican Fleabane is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for mexican fleabane as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 mexican fleabane go outside or overwinter — and where?

Plant it out within USDA 5–9 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 mexican fleabane can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Mexican Fleabane hardiness — frequently asked questions

Is mexican fleabane cold hardy?

Yes — mexican fleabane is genuinely cold hardy. Rated RHS H4 and USDA 5–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Mexican Fleabane is hardy across USDA 5–9; 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 mexican fleabane can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Mexican Fleabane is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is mexican fleabane?

Mexican Fleabane is rated USDA 5–9 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can mexican fleabane survive winter outside?

Plant it out within USDA 5–9 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 mexican fleabane below its minimum temperature?

It tolerates winter lows to about −10 to −5 °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.