Cold hardiness & minimum temperature

Is Leucanthemum × superbum 'Alaska' (Leucanthemum × superbum 'Alaska')cold hardy? Hardiness zone & min temp

Also called Alaska Shasta daisy, classic Shasta daisy.

More about leucanthemum × superbum 'alaska'

About Leucanthemum × superbum 'Alaska'

Leucanthemum × superbum 'Alaska' · also called Alaska Shasta daisy, classic Shasta daisy · flowering

Leucanthemum × superbum 'Alaska' is one of the oldest and hardiest single Shasta daisies, bearing large, simple white daisies with bright golden centres through midsummer. Exceptionally cold-tolerant and dependable, it is a cottage-garden mainstay and fine cut flower. It thrives in full sun and well-drained soil and is easily raised, including from seed.

Cold limit: USDA 4-9 · RHS H7 (-34-30°C)

Watch for — Crown rot in winter wet: Heavy, waterlogged soil rots the crown in cold months. Plant in well-drained ground, keep mulch off the crown, and divide congested clumps regularly.

What leucanthemum × superbum 'alaska''s hardiness rating actually means

Yes — leucanthemum × superbum 'alaska' is genuinely cold hardy. Rated RHS H7 and USDA 4-9, 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 4-9 — 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. Leucanthemum × superbum 'Alaska' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for leucanthemum × superbum 'alaska' 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 leucanthemum × superbum 'alaska' go outside or overwinter — and where?

Plant it out within USDA 4-9 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 leucanthemum × superbum 'alaska' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Leucanthemum × superbum 'Alaska' hardiness — frequently asked questions

Is leucanthemum × superbum 'alaska' cold hardy?

Yes — leucanthemum × superbum 'alaska' is genuinely cold hardy. Rated RHS H7 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Leucanthemum × superbum 'Alaska' is hardy across USDA 4-9; 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 leucanthemum × superbum 'alaska' can survive?

Minimum survivable temperature is roughly below about −20 °C. Leucanthemum × superbum 'Alaska' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is leucanthemum × superbum 'alaska'?

Leucanthemum × superbum 'Alaska' is rated USDA 4-9 and RHS H7 — Hardy in the severest European continental winters.

Can leucanthemum × superbum 'alaska' survive winter outside?

Plant it out within USDA 4-9 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 leucanthemum × superbum 'alaska' 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.