Cold hardiness & minimum temperature

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

Also called Sweet Woodruff, Sweet-Scented Bedstraw, Master of the Wood, Wild Baby's Breath.

More about sweet woodruff

About Sweet Woodruff

Galium odoratum · also called Sweet Woodruff, Sweet-Scented Bedstraw · herb

Galium odoratum is a fragrant, rhizomatous perennial groundcover native to the woodlands of Europe, Asia, and North Africa, producing whorls of narrow leaves and starry white flowers in late spring. It thrives in moist, well-drained soil in partial to full shade and spreads vigorously by underground rhizomes, making it an excellent low-maintenance groundcover beneath trees. The single most critical care point is providing adequate moisture during summer dry spells; drought forces the plant into early dormancy. Galium odoratum contains coumarin and is considered mildly toxic to pets if ingested in significant quantities.

Cold limit: USDA 4-9 · RHS H7 (-25 to 25°C)

What sweet woodruff's hardiness rating actually means

Yes — sweet woodruff 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. Sweet Woodruff is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for sweet woodruff 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 sweet woodruff 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 sweet woodruff can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Sweet Woodruff hardiness — frequently asked questions

Is sweet woodruff cold hardy?

Yes — sweet woodruff 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. Sweet Woodruff 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 sweet woodruff can survive?

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

What hardiness zone is sweet woodruff?

Sweet Woodruff is rated USDA 4-9 and RHS H7 — Hardy in the severest European continental winters.

Can sweet woodruff 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 sweet woodruff 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.