Harvesting, drying, and storing for potency

The difference between medicinal and useless is often just timing. Volatile oils in most herbs peak mid-morning after dew has evaporated but before the midday sun drives them off. Harvest then. Never harvest wet foliage — it moulds during drying.

For aerial parts (leaves, flowers), cut just before or at the start of flowering, when oil content is highest. For roots, dig in autumn when the plant has pulled energy underground, or early spring before growth resumes. Roots need washing and chopping before drying. For bark (willow, cramp bark), harvest in spring when sap is rising — it peels easily then.

Drying must happen fast but gently. Spread herbs in a single layer on racks or trays in a warm, dark, airy place — an airing cupboard, a shaded greenhouse, a room with a dehumidifier. Ideal temperature is 30–35°C. If it takes more than a week, your air is too damp and the herbs will lose colour and potency. Leaves and flowers are dry when they crumble. Roots are dry when they snap cleanly. Store immediately in airtight jars away from light. Label everything with plant name and harvest date. Dried herbs lose 50% of their potency after 1 year; replace annually.

Freezing works for some herbs. Lemon balm, basil, parsley, and coriander lose flavour and colour when dried but freeze well. Chop, pack into ice cube trays, cover with water or oil, freeze. Use within 6 months. This preserves flavour but not always medicinal compounds — volatile oils degrade in the freeze-thaw cycle. For medicine, dried is usually better.