When the first frost is forecast in autumn, the question arises: which herb must come in, which may stay out, and what do I do with the rest? Whoever indiscriminately hauls everything indoors torments the hardy species in the warm room, and whoever leaves everything outside loses the sensitive ones.
The solution is not a calendar but knowing the hardiness. Sort your herbs into three groups, then you know for each what to do. This article gives you the overview.
Frost is usually a hint, not a death sentence
Before you panic and bring everything in: for most native herbs, frost is no problem but a normal part of the year. A frost warning in the forecast is a hint to watch, not a reason to rescue. Only with the sensitive and the half-hardy species must you really act.
The key is to sort your herbs correctly once. After that, overwintering runs almost by itself.
The three winter groups
How to sort your herbs
- Hardy: stays outside
Thyme, sage, oregano, chives, mint, lovage and most native perennials survive winter in the bed without trouble. A little brushwood or leaves protects them further.
- Half-hardy: bright, cool quarters
Rosemary, bay and similarly Mediterranean herbs want to overwinter frost-free but cool and bright. Wet cold is their enemy, not a short frost. Details in Caring for and overwintering rosemary.
- Sensitive: in or resow
Basil and other warmth-lovers die at the first frost. They overwinter only warm and bright indoors, which is often laborious. Usually resowing in spring is worth more.
- In pots: protect the roots
Whatever the group: in a pot the root ball freezes through more easily than in the bed. Put pots against a sheltered house wall, on a polystyrene board and wrap them in severe frost.
What hardy herbs need
Surprisingly little. Thyme, sage and co. stay in the bed and partly die back or keep their foliage. A light protection of brushwood, leaves or some fleece helps evergreen species through clear, frosty, sunny winter days, on which they suffer more from drying out than from cold.
Important is to water evergreen herbs occasionally even in winter on frost-free days, when the soil is bone-dry. Because what many do not know: on sunny frost days they transpire water but cannot draw any from the frozen soil.
Sort by hardiness, not by calendar. Hardy stays outside, half-hardy comes in cool and bright, sensitive you resow in spring.
The core rule for overwintering
Frequently asked questions
Which herbs must come indoors in winter?
Only the half-hardy and the sensitive ones. Rosemary and bay want a bright, cool, frost-free quarters. Basil and other warmth-lovers survive only warm indoors. Hardy ones like thyme and sage stay outside.
Which herbs are hardy?
Thyme, sage, oregano, chives, mint, lovage and most native perennials. They survive winter in the bed, often without any protection. Evergreens appreciate a little brushwood against the winter sun.
Do I have to water hardy herbs in winter?
Occasionally yes on frost-free days, especially evergreens in pots. On sunny frost days they transpire water but cannot take any from the frozen soil and otherwise dry out. In open ground it is usually not necessary.
How do I protect potted herbs from frost?
Move the pots against a sheltered house wall, stand them on an insulating board instead of the cold ground and wrap them in fleece or jute in severe frost. That stops the root ball freezing through.
Is it worth overwintering basil?
Rarely. Basil is annual and hard to bring through winter indoors, because it would need to stand warm and very bright. Usually resowing in spring is easier and gives stronger plants.
