There are legal and ethical considerations when harvesting plants from the wild. It may be acceptable to harvest common plants but not rare or endangered plants. These should be protected. Before harvesting in the wild, check the conservation status of the plant and make sure it is not in any way threatened. Then choose a place where herbs are flourishing and away from pollution.
Herbs can, of course, easily be cultivated and many herbs may already be growing as weeds in your garden or community spaces. Starting your own herb garden is a good way to ensure an ongoing supply of fresh herbs, and provide all the animals in your area with much needed resources.
When harvesting leaves and flowers use a sharp knife or scissors and take care to minimise the damage to the living plant. Gloves may be needed if the plant is an irritant. Choose healthy plants and collect just enough for your needs. A good guide is to collect no more than a tenth of a plant, and then only from from every 10th plant. This will avoid over harvesting and allow a plant community to continue to thrive. If you are harvesting more than one plant, keep them apart to make sorting and identification easier later.
The best days for harvesting are warm, sunny days when any morning dew has evaporated. Any dampness will cause herbs you want to dry and store to rot, especially flowers. The best time of year depends on the part of the plant you are harvesting and the plants life-cycle. There is a season for everything. The idea is to harvest the part of the plant you want at the time when the plant is most focusing its energies there.
Here are some general guidelines:
- roots - winter (ideally after the above ground parts have died back and before the new shoots in spring have developed much)
- bark – winter
- shoots – spring
- leaves – spring and summer (generally before the flowers appear)
- flowers – at full bloom (before seeds start to develop)
- seeds – when ripe (before damp and rot sets in)
- fruits – when ripe (before rot sets in)
To be safe, never harvest a herb if you are not 100% certain as to its identity. There are many stories of a poisonous plant being used by mistake. A good example is well-known comfrey (Symphytum officinale) that, before flowering, can look very similar to the very toxic foxglove (Digitalis spp.).