Cold hardiness & minimum temperature

Is Daylily 'Black-eyed Stella' (Hemerocallis 'Black-eyed Stella')cold hardy? Hardiness zone & min temp

Also called Black-eyed Stella Daylily, Golden Eye Daylily.

More about daylily 'black-eyed stella'

About Daylily 'Black-eyed Stella'

Hemerocallis 'Black-eyed Stella' · also called Black-eyed Stella Daylily, Golden Eye Daylily · flowering

Black-eyed Stella is a compact reblooming daylily producing golden-yellow flowers with a striking dark purple-black eye zone on 45 cm scapes. A popular cultivar for its eye-catching two-tone patterning and reliable rebloom from early summer to frost. TOXIC — all Hemerocallis are potentially deadly to cats.

Cold limit: USDA 3-9 · RHS H7 (-30-38°C)

What daylily 'black-eyed stella''s hardiness rating actually means

Yes — daylily 'black-eyed stella' is genuinely cold hardy. Rated RHS H7 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. 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 below about −20 °C. Daylily 'Black-eyed Stella' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for daylily 'black-eyed stella' as it gets too cold:

It tolerates winter lows to about −20 °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 daylily 'black-eyed stella' 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 daylily 'black-eyed stella' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Daylily 'Black-eyed Stella' hardiness — frequently asked questions

Is daylily 'black-eyed stella' cold hardy?

Yes — daylily 'black-eyed stella' is genuinely cold hardy. Rated RHS H7 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Daylily 'Black-eyed Stella' 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 daylily 'black-eyed stella' can survive?

Minimum survivable temperature is roughly below about −20 °C. Daylily 'Black-eyed Stella' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is daylily 'black-eyed stella'?

Daylily 'Black-eyed Stella' is rated USDA 3-9 and RHS H7 — Hardy in the severest European continental winters.

Can daylily 'black-eyed stella' 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 daylily 'black-eyed stella' below its minimum temperature?

It tolerates winter lows to about −20 °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.