Cold hardiness & minimum temperature

Is Cotton Lavender (Santolina chamaecyparissus)cold hardy? Hardiness zone & min temp

Also called Cotton Lavender, Lavender Cotton, Santolina.

More about cotton lavender

About Cotton Lavender

Santolina chamaecyparissus · also called Cotton Lavender, Lavender Cotton · herb

Santolina chamaecyparissus is a compact, aromatic, evergreen subshrub native to rocky, dry terrain across the western and central Mediterranean basin, including Spain, France, Italy, and North Africa. It is prized for its finely divided, silver-grey, intensely fragrant foliage and cheerful, bright yellow, button-like flowerheads borne on erect stems in midsummer. The single most important care fact is that it must have sharply drained, lean soil in full sun; rich or wet soil causes the plant to become floppy, woody at the centre, and prone to root rot. Santolina is not listed by the ASPCA on its toxic plant lists, but the essential oil contains linalool and camphor which may be irritating to pets in large quantities; treat as mildly-toxic.

Cold limit: USDA 6–9 · RHS H5 (-15 °C to 35 °C)

Watch for — Root rot in wet or clay soil: Wet winters or poorly drained soil rapidly cause root and crown decay, especially in cold weather. Plant in raised beds or on slopes with added grit, and avoid autumn fertilisation.

What cotton lavender's hardiness rating actually means

Yes — cotton lavender is genuinely cold hardy. Rated RHS H5 and USDA 6–9, 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 6–9 — 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. Cotton Lavender is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for cotton lavender 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 cotton lavender go outside or overwinter — and where?

Plant it out within USDA 6–9 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 cotton lavender can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Cotton Lavender hardiness — frequently asked questions

Is cotton lavender cold hardy?

Yes — cotton lavender is genuinely cold hardy. Rated RHS H5 and USDA 6–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Cotton Lavender is hardy across USDA 6–9; 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 cotton lavender can survive?

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

What hardiness zone is cotton lavender?

Cotton Lavender is rated USDA 6–9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can cotton lavender survive winter outside?

Plant it out within USDA 6–9 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 cotton lavender 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.