How to Grow and Look After Winter Herbs
Some of your herbs will continue to grow in the winter months, however some simply don’t. For example, basil will not survive, and chives will lie dormant until the spring time, even if they are put in a cold frame. However there are a number of herbs that can be kept going, especially if you can grow them under glass.
Rosemary is able to withstand cold temperatures, and will do fine even out of a cold frame. you should be able to crop a little of it from if it’s a well established plant, but be careful not to overdo it. It is unlikely to grow too much unless it is a mild winter, but taking some of the old growth is fine and great for your Christmas roast potatoes!
Mint and parsley will keep growing, even through snow. It is slow growth, therefore if you want to use a lot then you need to make sure that you have a lot of individual plants. To encourage more growth you can move it into a cold frame. Parsley self-seeds, so after a season or two you may well have plenty of small plants in the corners of pots.
Sage and thyme will survive over the winter without protection, but you probably wont be able to crop any of them unless the winter is incredibly mild. They’re unlikely to grow much, and you don’t want to chop off all of their old growth or you will take away all of the plants reserves. If kept in a cold frame, they should grow at least a handful of fresh leaves over the winter period.
Oregano will die back altogether over winter, and even in a cold frame they may not generate any new growth. However, it will return in the spring unless the winter is unusually cold.