Cold hardiness & minimum temperature

Is Poke Milkweed (Asclepias exaltata)cold hardy? Hardiness zone & min temp

Also called poke milkweed, tall milkweed.

More about poke milkweed

About Poke Milkweed

Asclepias exaltata · also called poke milkweed, tall milkweed · flowering

A graceful, shade-tolerant North American native milkweed of woodland edges, bearing drooping clusters of greenish-white to pale lavender flowers on tall stems. Named for its pokeweed-like broad leaves, it suits dappled, moist sites where other milkweeds struggle. As an Asclepias it has milky sap and is toxic to cats, dogs and horses if eaten.

Cold limit: USDA 4-8 · RHS H5 (-34 to 30°C)

Watch for — Sparse availability: Less commonly cultivated, so plants and seed can be hard to source. Seek native-plant nurseries and cold-stratify seed for best results.

What poke milkweed's hardiness rating actually means

Yes — poke milkweed is genuinely cold hardy. Rated RHS H5 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 4-8 — 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 −15 to −10 °C. Poke Milkweed is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for poke milkweed as it gets too cold:

It tolerates winter lows to about −15 to −10 °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 poke milkweed go outside or overwinter — and where?

Plant it out within USDA 4-8 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 poke milkweed can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Poke Milkweed hardiness — frequently asked questions

Is poke milkweed cold hardy?

Yes — poke milkweed is genuinely cold hardy. Rated RHS H5 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Poke Milkweed is hardy across USDA 4-8; 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 poke milkweed can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Poke Milkweed is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is poke milkweed?

Poke Milkweed is rated USDA 4-8 and RHS H5 — Hardy in most of the UK and in cold winters.

Can poke milkweed survive winter outside?

Plant it out within USDA 4-8 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 poke milkweed below its minimum temperature?

It tolerates winter lows to about −15 to −10 °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.