Cold hardiness & minimum temperature

Is Woodruff (Galium odoratum)cold hardy? Hardiness zone & min temp

Also called sweet woodruff, woodruff, master of the wood.

More about woodruff

About Woodruff

Galium odoratum · also called sweet woodruff, woodruff · herb

Sweet woodruff is a low, spreading woodland groundcover with whorls of bright green, star-shaped leaves and a froth of tiny white spring flowers. Dried foliage smells of new-mown hay from its coumarin content and was used to scent linen and flavour drinks. It carpets shady, moist ground quickly, making excellent weed-suppressing cover beneath shrubs and trees.

Cold limit: USDA 4-8 (outdoor groundcover) · RHS H6 (5-21°C)

What woodruff's hardiness rating actually means

Yes — woodruff is genuinely cold hardy. Rated RHS H6 and USDA 4-8 (outdoor groundcover), 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 4-8 (outdoor groundcover) — 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. Woodruff is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for woodruff 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 woodruff go outside or overwinter — and where?

Plant it out within USDA 4-8 (outdoor groundcover) 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 woodruff can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Woodruff hardiness — frequently asked questions

Is woodruff cold hardy?

Yes — woodruff is genuinely cold hardy. Rated RHS H6 and USDA 4-8 (outdoor groundcover), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Woodruff is hardy across USDA 4-8 (outdoor groundcover); 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 woodruff can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Woodruff is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is woodruff?

Woodruff is rated USDA 4-8 (outdoor groundcover) and RHS H6 — Hardy throughout the UK and northern Europe.

Can woodruff survive winter outside?

Plant it out within USDA 4-8 (outdoor groundcover) 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 woodruff 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.