Caring for herbs
Pinch your plants back regulary, except rosemary, by removing the flower heads or the tips of the stems to encourage them to become bushier and remain compact.
Plants grown for their seeds, including aniseed, coriander, fennel and dill, should be allowed to flower.
If you are growing herbs in pots, check them daily to see if they need watering. With the exception of mint and chervil, herbs generally prefer rather dry soil.
Fertilizing your plants
Fertilize herbs grown in pots once every three weeks with a fertilizer like 4-3-4 (seaweed and fish emulsion). You can also add a slow-release granular fertilizer (14-14-14) to the soil near the top of each pot at the start of the season.
Provided that you have improved the soil before planting herbs directly in the ground, it will be enough to fertilize when you transplant them. Over-fertilizing will only dilute the concentration of the essential oils that give them their flavour.
Pests
Aromatic plants are rarely attacked by insects. Instead, they act as repellents, and their flowers attract bees and other helpful insects.
If a plant does become infested, spray it all over with lukewarm water. If the problem persists, spray the plant with a mixture of water and mild soap.
If the plant is a perennial, cut it back and it will regrow. You can also pick the insect larvae off by hand.
In a herb garden or vegetable plot, rotate your crops each year so as to prevent disease-causing pathogens from taking hold.