Cold hardiness & minimum temperature

Is Drummond's Aster (Symphyotrichum drummondii)cold hardy? Hardiness zone & min temp

Also called Drummond's aster, Drummond's blue-wood aster, Heart-leaved aster.

More about drummond's aster

About Drummond's Aster

Symphyotrichum drummondii · also called Drummond's aster, Drummond's blue-wood aster · flowering

Symphyotrichum drummondii is a versatile native perennial found in open woodlands, savannas, woodland edges, and disturbed habitats across the central and eastern United States. It produces masses of small (roughly 1.5 cm) white daisy flowers — often ageing to pale blue-purple — on arching, panicle-branched stems from September to October, making it one of the best late-season nectar sources for butterflies. Uniquely among native asters, it tolerates a wide range of light conditions from full sun to moderate shade, adapting to woodland understory as well as open borders. Symphyotrichum drummondii is non-toxic to cats and dogs.

Cold limit: USDA 3-9 · RHS H6 (-35 to 35°C)

What drummond's aster's hardiness rating actually means

Yes — drummond's aster is genuinely cold hardy. Rated RHS H6 and USDA 3-9, 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 3-9 — 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. Drummond's Aster is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for drummond's aster 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 drummond's aster go outside or overwinter — and where?

Plant it out within USDA 3-9 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 drummond's aster can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Drummond's Aster hardiness — frequently asked questions

Is drummond's aster cold hardy?

Yes — drummond's aster is genuinely cold hardy. Rated RHS H6 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Drummond's Aster is hardy across USDA 3-9; 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 drummond's aster can survive?

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

What hardiness zone is drummond's aster?

Drummond's Aster is rated USDA 3-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can drummond's aster survive winter outside?

Plant it out within USDA 3-9 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 drummond's aster 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.