Cold hardiness & minimum temperature

Is Forget-me-not (Myosotis sylvatica)cold hardy? Hardiness zone & min temp

Also called wood forget-me-not, garden forget-me-not.

About Forget-me-not

Myosotis sylvatica · also called wood forget-me-not, garden forget-me-not · flowering

Forget-me-nots are biennial woodland edge plants with clouds of sky-blue (and rare pink/white) tiny flowers in spring. Self-seed prolifically — almost too well. Pet-safe and a popular underplanting for tulips and bulbs.

Garden forget-me-not (Myosotis sylvatica) is a tufted, hairy short-lived perennial native to woodland and rocky places, including the British Isles, almost always grown as a biennial for spring color.

Self-seeds freely and sometimes aggressively, persisting in the garden for years; in formal beds plants are pulled after flowering to control spread.

Cold limit: USDA 3-8 · RHS H6 (10-21°C)

Sources: rhs.org.uk, missouribotanicalgarden.org

What forget-me-not's hardiness rating actually means

Yes — forget-me-not is genuinely cold hardy. Rated RHS H6 and USDA 3-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 3-8 — 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 −20 to −15 °C. Forget-me-not is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for forget-me-not as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 forget-me-not go outside or overwinter — and where?

Plant it out within USDA 3-8 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 forget-me-not can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Forget-me-not hardiness — frequently asked questions

Is forget-me-not cold hardy?

Yes — forget-me-not is genuinely cold hardy. Rated RHS H6 and USDA 3-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Forget-me-not is hardy across USDA 3-8; 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 forget-me-not can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Forget-me-not is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is forget-me-not?

Forget-me-not is rated USDA 3-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can forget-me-not survive winter outside?

Plant it out within USDA 3-8 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 forget-me-not below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.