Cold hardiness & minimum temperature

Is Red Sheep Laurel (Kalmia angustifolia f. rubra)cold hardy? Hardiness zone & min temp

Also called Red Sheep Laurel, Sheep Laurel, Lambkill, Wicky.

More about red sheep laurel

About Red Sheep Laurel

Kalmia angustifolia f. rubra · also called Red Sheep Laurel, Sheep Laurel · flowering

Kalmia angustifolia f. rubra is a colony-forming evergreen shrub native to the bogs, heathlands, and open woodlands of eastern North America, selected for its rich deep-red bowl-shaped flowers borne in dense lateral clusters in early summer — deeper in colour than the standard pink-flowered species. It thrives in moist, acidic soil in full sun to partial shade and spreads steadily by rhizomes. The most important care fact is that it demands acidic, lime-free soil; it is also highly toxic to livestock and pets and should not be grown where animals can browse it.

Cold limit: USDA 2-6 · RHS H5 (-40 to 30 °C)

What red sheep laurel's hardiness rating actually means

Yes — red sheep laurel is genuinely cold hardy. Rated RHS H5 and USDA 2-6, 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 2-6 — 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. Red Sheep Laurel is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for red sheep laurel 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 red sheep laurel go outside or overwinter — and where?

Plant it out within USDA 2-6 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 red sheep laurel can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Red Sheep Laurel hardiness — frequently asked questions

Is red sheep laurel cold hardy?

Yes — red sheep laurel is genuinely cold hardy. Rated RHS H5 and USDA 2-6, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Red Sheep Laurel is hardy across USDA 2-6; 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 red sheep laurel can survive?

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

What hardiness zone is red sheep laurel?

Red Sheep Laurel is rated USDA 2-6 and RHS H5 — Hardy in most of the UK and in cold winters.

Can red sheep laurel survive winter outside?

Plant it out within USDA 2-6 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 red sheep laurel 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.