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Notebook · Guide 8 October 2026 · seasonal

Rosemary and lavender dying in winter: it's the wet, not the cold

Mediterranean herbs mostly die of cold, waterlogged roots, not frost. Sharp drainage, no saucers, pots raised off the ground and no hard autumn pruning get them through.

seasonal

Every February someone looks at a grey, brittle rosemary or a collapsed lavender and blames the frost. Usually the frost isn't to blame. These plants come from dry, stony hillsides. What usually kills them is weeks of cold, sodden soil around the roots: as the RHS puts it, cold, wet compost can make rosemary roots rot and die. The same goes for sage and thyme. Fix the drainage and most of your winter losses stop.

01At a glance

  • The real killer: roots sitting in cold, waterlogged soil or compost for weeks on end.
  • In the ground: on heavy soil, plant on a mound or ridge, or in a raised bed. Never plant lavender in winter.
  • In pots: remove the saucer, raise the pot on bricks or pot feet, and move it into the rain shadow of a wall.
  • Pruning: leave them alone now. None of the RHS timings for these herbs is an autumn one, and none of them reliably regrows from old wood.
  • Cold still matters a little: established rosemary survives down to about -8°C. French lavender and some thymes are less hardy.

02In the ground

  • Choose the sunniest, best-drained spot you have. All four want full sun and light, free-draining soil.
  • On heavy clay, lift the roots out of the wet. The RHS suggests a raised bed or a container for all four, and a 20–30cm mound or ridge for lavender.
  • Plant in spring, not winter. The RHS warns that young lavender planted in winter is vulnerable to rotting in cold, wet soil.
  • For thyme in a very wet area, the RHS suggests a cloche over winter to keep the worst of the rain off.

03In pots: the winter routine

A pot that can't drain is a bucket. Do this in late autumn, before the wet sets in.

  1. Check the drainage holes are clear.
  2. Take the saucer away.
  3. Raise the pot on bricks or pot feet so water can run straight out of the holes.
  4. Move it into the rain shadow of a wall or another sheltered spot. In a very wet spell, the RHS suggests moving pots under temporary cover if the compost becomes sodden.
  5. Keep it on the dry side. Only water if the compost is genuinely dry.
  6. Protect the roots from hard frost. Pot roots are less insulated than roots in the ground. Group pots together and wrap them in old blankets or reused bubble wrap, or move them somewhere more sheltered.

When you next repot, mix horticultural grit into the compost. The RHS suggests up to 25 per cent by volume for rosemary, lavender and thyme.

04Leave the secateurs in the shed

Here's when the RHS says to prune each one:

  • Rosemary: a light trim once a year, after flowering.
  • Lavender: in late summer, just after flowering. A light tidy in spring if frost has damaged the tips.
  • Sage: lightly, in mid- to late spring.
  • Thyme: mid- to late spring and/or soon after flowering.

All four share the same warning: don't cut back into old, bare wood. It may not reshoot. An old, leggy plant is better replaced with a young one grown from a cutting.

05Check for rosemary beetle

Rosemary beetle feeds on rosemary, lavender, sage and thyme, and the RHS says it is most active from August to April, feeding through mild spells in autumn, winter and spring.

  • Adults: shiny, 6–7mm long, with metallic purple and green stripes.
  • Larvae: greyish-white with darker stripes, up to 8mm.
  • Damage: leaves eaten down to short, greyish-brown stumps, sometimes flowers too.

In most cases the plant's overall health isn't affected, and the RHS says control is usually unnecessary. If numbers bother you, tap the branches over a sheet of newspaper and collect what falls.

06Is it the wet, the cold, or something else?

  • Greying, dropping needles on rosemary, or a whole plant collapsing, in soil or compost that stays wet: waterlogged roots.
  • Damage straight after a severe frost or bitter wind, in a well-drained spot: cold. The RHS says harsh frosts and cold winds can still damage rosemary, and in extreme cases kill it. Leave any tidying until spring, when you can see what's alive.
  • Chewed, stumpy leaves with small striped beetles or grubs: rosemary beetle.
  • French lavender gone over its first winter outside: it's less hardy than English lavender. Next year, give it a pot you can move under cover.
Save your money
Don't buy pot feet if you have bricks. Anything that lifts the base clear does the job.
Don't feed them now. These are lean-soil plants: the RHS says rosemary in the ground needs no feeding, and container plants don't need feeding in winter.
Grow your replacements for free. Take cuttings in summer so a woody old plant can be retired without a trip to the garden centre.
Fleece only for the worst nights. For very cold spells the RHS suggests a temporary cover of fleece, hessian or an old bedsheet.

Before planting lavender where children or pets play, check the safety flags on our lavender profile.

How we checked this

Every care and safety claim on this page is verified against horticultural and veterinary sources.

Sources: RHS — How to grow rosemary · RHS — How to grow lavender · RHS — How to grow sage · RHS — How to grow thyme · RHS — Rosemary beetle · RHS — Growing plants in containers · RHS — Container maintenance

Checked 8 October 2026. If our advice ever conflicts with the RHS, believe them and tell us.