Herbs can largely be left to do their thing, however late summer sees many herbs in full bloom, and this means that there are a few little jobs that are worth doing around about now.
Basil – pinch stems back to leave a few pairs of young leaves on each stem. This will encourage the plant to bush out rather than going to seed, so you’ll prolong its life. Use the leaves that you pinch off to make a pesto.
Borage – Borage will readily self-seed so deadhead regularly if you’d rather keep the plants to a minimum!
Chives – Cut them right back – they should have already flowered by now, and the seedheads will be forming (these will self seed easily). By cutting them back you can expect them to grow back and flower over the autumn.
Lavender – cut back by about a third once it has finished flowering. Be careful to leave some strong green shoots on the plant.
Marjoram & Oregano – cut them back once they have flowered (and before the seeds set in as they self seed easily!) You’ll get some good growth between now and late Autumn when you can cut them back again.
Mint – You could cut back mint that is looking tired, or wait until the end of autumn.
Rosemary – prune lightly (just a trim!) every so often between now and mid-autumn to keep the plant healthy and bushy.
Sage – Trim back after it has flowered
Thyme – trim back lightly after flowering