Which herbs survive a UK winter outside?
Which herbs are genuinely hardy, which are annuals that were always going to die, which need protection, and the winter wet that kills more herbs than frost does.
- Difficulty
- beginner
- Time
- 25 min
- Read
- 4 min
Short answer
Thyme, sage, chives, mint, oregano, fennel, bay and most rosemary are hardy outdoors in most of the UK. Basil is a tender annual and always dies. Coriander, dill and parsley are short-lived and will not overwinter usefully. Tender rosemary, lemon verbena and French tarragon need shelter, and the real winter killer is wet soil, not cold.
Herbs get lumped together as one category and they are not. Some are hardy perennials that will outlive you, some are Mediterranean subshrubs vulnerable to wet rather than cold, and some are annuals that were always going to die in October regardless of what you did. Knowing which is which stops a lot of pointless fleece and a lot of unnecessary disappointment.
Step by step
- Separate the annuals out first — nothing will save them.Basil is a tender annual killed by the first cold night. Coriander, dill and chervil are short-lived annuals. Parsley is a biennial that grows leaf in year one and flowers in year two. None of these overwinters usefully outdoors and no protection changes that.
- Identify the reliably hardy perennials.Chives, mint, thyme, sage, oregano and marjoram, fennel, lovage, sorrel and horseradish all come through a British winter outdoors. Several die back to the ground and reappear in spring, which is normal and not a failure.
- Treat the Mediterranean subshrubs as a wet problem, not a cold one.Rosemary, sage, thyme and lavender are hardy to temperatures a UK winter rarely reaches, but they rot in cold saturated soil. Sharp drainage, a sunny position and a gravel mulch instead of compost do far more for their survival than fleece ever will.
- Give bay a sheltered position and watch for wind.Bay is hardy in most of the UK but the leaves scorch brown in cold drying winds and it can be cut back in a severe winter. A sheltered spot, or a pot moved against a wall, avoids most of it. It usually reshoots from old wood even after serious damage.
- Protect the genuinely tender ones properly.Lemon verbena, French tarragon, some prostrate and variegated rosemarys, and scented pelargoniums need a frost-free but cool place: a cold greenhouse, a porch, an unheated conservatory. Keep them barely watered and give them light. Warmth is a mistake.
- Move pots off the ground and against a wall.Herbs in containers are far more vulnerable than the same plants in the ground, because the rootball freezes from all sides and the compost stays wet. Pot feet, a sheltered wall and free drainage solve most of it.
- Do not cut woody herbs back in autumn.It stimulates soft growth that cannot harden, and leaves open wounds through the wettest months. Prune Mediterranean herbs after flowering in late summer and tidy them again in spring.
- Pot up a few plants for winter picking.Chives, mint and parsley lifted, divided and potted in autumn will give useful pickings on a cool windowsill or in a cold greenhouse. Mint in particular responds well and produces fresh shoots weeks ahead of the outdoor plant.
- Preserve the surplus before the frosts.Cut and freeze or dry the herbs that will disappear. Soft herbs freeze better than they dry; woody ones dry well. This is a better use of September than trying to keep an annual alive.
- Cut back and mulch the herbaceous perennials.Mint, fennel, lovage and sorrel die down naturally. Cut the dead growth off in late autumn or leave it until spring, and mulch around the crown.
Tips
- Mint is not just hardy but invasive. Left in open ground it will take over, so keep it confined to a pot even when overwintering it.
- French tarragon is the one worth having for flavour and is the less hardy of the two; Russian tarragon is tougher and much less good to eat. Check which you have before deciding how much trouble to take.
- Snow is not the enemy. Weeks of saturated cold soil around the crown is what kills Mediterranean herbs.
- A herb that dies back completely to the ground in November — mint, chives, tarragon, fennel — is behaving normally. Do not dig it up in February assuming it has died.
Common mistakes
- Trying to overwinter basil on a windowsill — It is a tender annual that needs high light and warmth. It usually goes leggy and mildewed and dies by January. Sow fresh in spring.
- Fleecing a rosemary in a wet clay bed — Cold is not what is killing it. The fleece holds moisture and makes the actual problem worse. Improve the drainage instead.
- Cutting woody herbs back hard in autumn — It provokes soft growth going into the cold and opens wounds through the wet season, which is the opposite of what you want.
- Bringing hardy herbs indoors into a warm room — They need a cold dormancy. In a heated room they grow soft, pale and pest-ridden and are much weaker come spring.
Questions people ask
Will my rosemary survive the winter?
In most of the UK, yes, provided it is in a sunny, free-draining position. Rosemary is killed by cold wet soil far more often than by low temperature, so drainage is the deciding factor.
Can I keep basil going through winter?
Not usefully. It is a tender annual that needs warmth and strong light, neither of which a British windowsill supplies in January. Sow fresh in spring.
My mint has vanished — is it dead?
Almost certainly not. Mint dies right back to the ground each winter and reappears in spring, often more vigorously than before.
Do herbs in pots need protection?
More than the same plants in the ground, because the rootball freezes from all sides and stays wet. Raise the pots on feet, move them against a sheltered wall, and make sure they drain.