These herbs are prone to bolting, so be sure to cut them back regularly to keep them nice and leafy for longer.
Bolting is when the plant goes to produce flowers and seeds, which for these cool-loving herbs often happens rather suddenly during the summer months. Once they do this, you can still use the leaves, but you own’t have as plentiful a supply and the taste will change slightly and stalks will toughen.
For chervil, coriander and parsley, you’ll get a longer supply if you regularly harvest, treating them as cut and come again. You can simply cut back to 5-8cm, which will leave the new baby leaves to come through from the centre.
It is also worth growing these herbs in a cooler spot, light shade or partial shade, and keep them well watered to keep the soil temperature cool. If you are growing them in full sun, try mulching them to keep the soil temperature down as well.