The whole process of harvesting and storing the herbs should be carried out as carefully and speedily as possible.
Gather the leafy herbs for drying in the morning of a dry day when the dew has dried, just before the plant comes into flower.This is when the volatile oils contained in the leaves are at their highest and on this the flavour , colour and scent depend.
During the season annual herbs can be cut to within 4-5 in (10- 12,5 cm) from the ground and in the autumn they can be cut right down to the ground . Perennials such as fennel, lovage and sweet cicely can be cut back to one third of their growth. Shrubby perennials like sage and hyssop can be kept neat by taking a few sprigs at a time and cutting back to half the year’s growth in the autumn. Scissors or sharp shears should be used to collect the herbs, as breaking the stem or pulling at leaves will only damage the plant. Care should be taken to avoid bruising the leaves. After gathering the herbs discard any leaves that are very muddy or damaged. The herbs should then be quickly but carefully washed in tepid water.
Flowering tops such as rosemary, hyssop, thyme and mugworth, should be gathered when the flowers are just beginning to open. Flowers and petals should be collected when the flowers are fully open – often on a daily basis to ensure they are picked when whole and unblemished.
Seeds of dill, fennel, caraway and sunflower are collected in autumn. When the heads of eh plants have turned brown the stem can be tapped each day to test if the seeds are ripe. If the seeds begin to fall when tapped, the herb should be cut down and collected in a box on a dry day. Tie the stems together and hang them upside down in a paper bag so that all the seeds will be saved.
Berries should be gathered when the fruit is fully ripe and firm and the colour is at its best. They will not dry successfully if they are at all soft or shrivelled and they should be handled as little as possible.
Harvest roots in autumn when the leaves have died down. If a plant such as marsh mallow is being lifted for division in spring, pieces of the root can be removed for drying at the same time.
Herbs should be stored in dark-coloured glass, screw-top jars immediately they are dry, otherwise they pick up moisture from the air. They should not be stored in tins unless they are first placed in a cotton bag because contact with the tin can damage the flavour and aroma of the herb. Dried herbs should not be stored for longer than a winter season, or at most nine months, as they lose their colour, scent and flavour of kept for too long.