Cold hardiness & minimum temperature

Is Comb Speedwell (Veronica pectinata)cold hardy? Hardiness zone & min temp

Also called Comb Speedwell, Comb-leaved Speedwell.

More about comb speedwell

About Comb Speedwell

Veronica pectinata · also called Comb Speedwell, Comb-leaved Speedwell · flowering

Comb Speedwell is a low creeping perennial from Turkey and the eastern Mediterranean, forming a dense silvery-grey mat covered in bright blue flowers with a white eye in spring. The deeply toothed, comb-like leaves give the species its name. Ideal for rock gardens, dry walls, and between paving; highly drought-tolerant and exceptionally heat-resilient.

Cold limit: USDA 5-9 · RHS H5 (-15°C to 35°C)

Watch for — Winter wet rot: The primary threat in cool, wet climates. Prolonged winter moisture on the mat causes crown and stem rot. Ensure extremely sharp drainage; plant on a slope or in a raised bed, and avoid mulching over the crown.

What comb speedwell's hardiness rating actually means

Yes — comb speedwell is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 5-9 — 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 about −15 to −10 °C. Comb Speedwell is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for comb speedwell as it gets too cold:

It tolerates winter lows to about −15 to −10 °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 comb speedwell go outside or overwinter — and where?

Plant it out within USDA 5-9 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 comb speedwell can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Comb Speedwell hardiness — frequently asked questions

Is comb speedwell cold hardy?

Yes — comb speedwell is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Comb Speedwell is hardy across USDA 5-9; 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 comb speedwell can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Comb Speedwell is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is comb speedwell?

Comb Speedwell is rated USDA 5-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can comb speedwell survive winter outside?

Plant it out within USDA 5-9 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 comb speedwell below its minimum temperature?

It tolerates winter lows to about −15 to −10 °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.