Cold hardiness & minimum temperature

Is Sticky Primrose (Primula viscosa)cold hardy? Hardiness zone & min temp

Also called Sticky primrose, Clammy primrose.

More about sticky primrose

About Sticky Primrose

Primula viscosa · also called Sticky primrose, Clammy primrose · flowering

Primula viscosa is a compact evergreen alpine perennial native to the limestone and acidic scree of the western Alps and Pyrenees, where it grows at elevations between 1,500 and 3,000 metres. The entire plant — stems, leaf undersides, and flower stalks — is covered in sticky, glandular hairs that trap small insects, reducing water loss and providing some protection from grazing. It produces clusters of fragrant, pink to rose-purple flowers with a yellow eye in spring. Excellent drainage and protection from winter wet are the non-negotiable conditions for success. This species is toxic to cats, dogs, and horses.

Cold limit: USDA 3-6 · RHS H5 (-20 to 18°C)

Watch for — Crown rot from winter wet: The most common cause of plant loss in cultivation; grow in a raised rock garden pocket, alpine trough, or alpine house with overhead protection from late autumn to spring.

What sticky primrose's hardiness rating actually means

Yes — sticky primrose is genuinely cold hardy. Rated RHS H5 and USDA 3-6, 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 3-6 — 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. Sticky Primrose is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for sticky primrose 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 sticky primrose go outside or overwinter — and where?

Plant it out within USDA 3-6 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 sticky primrose can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Sticky Primrose hardiness — frequently asked questions

Is sticky primrose cold hardy?

Yes — sticky primrose is genuinely cold hardy. Rated RHS H5 and USDA 3-6, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Sticky Primrose is hardy across USDA 3-6; 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 sticky primrose can survive?

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

What hardiness zone is sticky primrose?

Sticky Primrose is rated USDA 3-6 and RHS H5 — Hardy in most of the UK and in cold winters.

Can sticky primrose survive winter outside?

Plant it out within USDA 3-6 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 sticky primrose 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.