Cold hardiness & minimum temperature

Is Keiske's Leucothoe (Leucothoe keiskei)cold hardy? Hardiness zone & min temp

Also called Keiske's Leucothoe, Dog Hobble, Fetterbush.

More about keiske's leucothoe

About Keiske's Leucothoe

Leucothoe keiskei · also called Keiske's Leucothoe, Dog Hobble · flowering

Leucothoe keiskei is a low, arching evergreen shrub native to rocky mountain woodland slopes in Japan. It thrives in cool, humus-rich, acidic soil with partial to full shade and even moisture; overwatering is the most common cause of decline. Foliage turns striking ruby-red in winter, and small white urn-shaped flowers appear in late spring. Toxic to dogs, cats, and horses due to grayanotoxins.

Cold limit: USDA 6-9 · RHS H5 (-15 to 25°C)

What keiske's leucothoe's hardiness rating actually means

Yes — keiske's leucothoe is genuinely cold hardy. Rated RHS H5 and USDA 6-9, 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 6-9 — 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 −15 to −10 °C. Keiske's Leucothoe is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for keiske's leucothoe 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 keiske's leucothoe go outside or overwinter — and where?

Plant it out within USDA 6-9 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 keiske's leucothoe can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Keiske's Leucothoe hardiness — frequently asked questions

Is keiske's leucothoe cold hardy?

Yes — keiske's leucothoe is genuinely cold hardy. Rated RHS H5 and USDA 6-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Keiske's Leucothoe is hardy across USDA 6-9; 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 keiske's leucothoe can survive?

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

What hardiness zone is keiske's leucothoe?

Keiske's Leucothoe is rated USDA 6-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can keiske's leucothoe survive winter outside?

Plant it out within USDA 6-9 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 keiske's leucothoe 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.