Some herbs, such as rosemary and bay can be harvested right through the winter, as can thyme if you cut back your plants immediately after they had finished flowering and have plenty of sturdy new growth. However, if you have not previously taken your scissors to the thyme then it is best to do so now to keep the plant in good shape. Whilst you herb plant will not look at its most attractive after this, such action will reap rewards next spring. Cutting back now will encourage new growth from the base of the plant and ensure that you do not end up with a straggly, bare centred plant next year.
It is imperative however not to leave this too late as any frost may damage the new growth which the plant will need to protect it over winter. Other herb plants which will benefit from a trim include lavender, winter savory and hyssop.
Don’t worry- there is no need to waste your trimmings. Any cut stems can be dried and stored in dark jars (or if you don’t have any, clear jars will do in a dark cupboard). Other herbs which can be dried and stored include oregano, marjoram, sage, mint, hyssop and basil. Freezing is also an alternative, a convenient way of doing this is to chop up the herbs and freeze them in ice cubes. (See photo)
Try this with mint, parsley and tarragon.
Mint plants need slightly more than a trim. They need to be cut right back to ensure a healthy supply of fresh leaves in early spring. If your mint is in a pot which it has filled then remove it from the pot, saw it in half and re-pot the two halves into separate pots. This will avoid the problem of rot which affects many pot grown mints which have outgrown their original container.
Tender herb plants will need to be lifted before the first frosts otherwise the frost will kill them. These include lemon grass and basil. The timing of this will really depend on where you live. Some areas need not worry about this for another few weeks but it is better to be safe than sorry. As a rule of thumb this is a job you need to do before the night time temperatures drop below 4°C. Cut back the herbs once lifted and keep in a frost free environment for winter. It is important to keep watering to a minimum during this time and avoid centrally heated rooms if at all possible.
Half hardy herbs that will need protecting with fleece if they remain outside include lemon verbena and blackcurrant sage. Here in Sligo ours survived last winter without protection against a south facing wall but there is always a risk of damage. Bay trees also like a position sheltered from winter winds.
Any herb plants growing in containers should be moved against the wall of the house so that the wall will act as a kind of storage heater. If you can’t move your pots then wrapping them in bubble wrap is an alternative. The problem is not the frost on the foliage but the fact that in very cold spells the water in the pots becomes frozen and the roots cannot take up any liquid. If you are moving your herb planters next to the wall bear in mind that the leaves may shelter them from the rain and the odd watering may be required.