Cold hardiness & minimum temperature

Is Crosswort (Cruciata laevipes)cold hardy? Hardiness zone & min temp

Also called Crosswort, Smooth Bedstraw.

More about crosswort

About Crosswort

Cruciata laevipes · also called Crosswort, Smooth Bedstraw · flowering

Crosswort (Cruciata laevipes, syn. Galium cruciata) is a low-growing native perennial of the Rubiaceae family, widespread across the UK in woodland edges, hedgerows, and calcareous grassland. Its whorls of four hairy, cross-shaped leaves give the plant its name, and tiny pale yellow honey-scented flowers appear from April to June. The most important care point is that it needs moderately fertile, well-drained, neutral to calcareous soil and will spread by rhizomes to form loose ground-covering mats. No records of toxicity to cats or dogs exist; it is considered of low concern but not formally listed as pet-safe by ASPCA.

Cold limit: USDA 4-8 · RHS H6 (-15–25 °C)

What crosswort's hardiness rating actually means

Yes — crosswort is genuinely cold hardy. Rated RHS H6 and USDA 4-8, 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 4-8 — 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. Crosswort is built for winter — once established it takes hard frost and snow in its stride.

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

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

Crosswort hardiness — frequently asked questions

Is crosswort cold hardy?

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

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

What hardiness zone is crosswort?

Crosswort is rated USDA 4-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can crosswort survive winter outside?

Plant it out within USDA 4-8 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 crosswort 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.