Basil (Ocimum basilicum) -Because Basil is an annual herb it has the tendency to form flowers quite quickly. Unfortunately letting it flower does have an effect on the taste of the leaves. As soon as you see the buds being formed, pinge out the flower head together with the two leaves underneath it. If you are too late, not all is lost, the flowers heads can be consumed just like the leaves. A basil variety "Fin vert de Marseille" bolts less than the other varieties.
Chives (Allium schoenoprasum) - From early spring onwards you can already start harvesting the chives. To enjoy the new fresh shoots it is best to cut down a part of the chives every 15 days to the ground. Again it is preferable not to let the chives flower, as the young shoots taste the best, but the flowers are very attractive and have a taste all of their own, sowell, let some of them come into flower. There exists a variety called Allium lusitanicum that does not flower.
Tarragon (Artimisia dracuncules) - It is quite important to make sure you've bought the right type of Tarragon. Very often the shops sell the Russian Tarragon (Artimisia dracunculoides) which has hardly any flavour. The real Tarragon is called (Artemisia dracunculus). As you can see the similarity in name is confusing. The leaves have to be cut back regularly during the season. In the summer when you harvest the leaves, do so by cutting down a third of the shoots, to avoid drying out of the plant.
Sage (Salvia officinalis) - Harvest by using a secateur from March to September, just the extreme ends of the plant. To keep the Salvia in a nice shape, cut it down to 10 cm away from the soil, every autumn.
Thyme (Thymus) - Thyme can be used the whole year round. Snip off some of the shoots as needed. From June to August, it does need to be pruned regularly, try to maintain a dome form. Looks much prettier.
Rosemary (Rosmarinus officinalis) - Use a secateur to harvest this year's shoots. When harvesting in the winter, do so sparingly. The pruning is done after the flowering around April to May. The purpose of the pruning is to make sure that the base does not dry out.
Bibliography : Rustica