- Only gather plants that you are certain of their identity. There are many herb plants that are look-a-likes, and are poisonous. If you are not certain, do not gather.
- Know which part of the plant you need. Take only what you need, and be careful to not damage the plant. Always leave enough for the plant to be able to reproduce next year. If you want to grow a plant in your garden, gather the seeds for propagation rather than transplant them from the wild.
- Dry herbs quickly and thoroughly. If any moisture is left behind, this can cause mold. They can be dried in the sun, or in an herb dehydrator. Herbs should be stored in paper bags, or glass jars. Be sure to label as to what it is, where it was picked, and remember to put a date on the container. Herbs store well if dried properly.
Aerial parts are best collected in the midst of flowering, giving a mixture of leaves, stems, flowers, and seed heads. Skullcap, for example, can be collected when about half the flowers have formed the characteristic cap-shaped pod. Large leaves, like burdock, can be harvested and dried individually. Smaller leaves, like lemon balm, are best left on the stem. Gather deciduous leaves just before flowering. Evergreen herbs, like rosemary, can be harvested throughout the year. If using all aerial parts, harvest in mid-flowering, giving a mixture of all the parts. Remove obvious dirt, grit, and insects!
Bark is generally best collected in the fall when the sap is falling. This minimizes damage to the plant. Remove small, vertical strips just a few inches long. Brush softly with a tooth brush to remove dirt, moss, or insects. Remove thin, vertical strips of no more than a few inches. Break the pieces into small pieces, spread on trays, and let dry. Never remove all the bark, or even a band of bark completely around a tree. This will kill the whole tree.
Bulbs are harvested after the aerial parts have wilted. Collect garlic bulbs quickly as they tend to sink downward after the leaves have wilted, and are then difficult to find.
Flowers should be collected when fully open and handled carefully as they are easily damaged. Harvest after the morning dew has evaporated and when fully open. Cut the flower heads from the stems and dry whole on trays. Small flowers, like lavender, can be dried on their stems; but, if the stem is fleshy, like mullein, the flowers must be removed and dried individually.
Fruit berries and other fruits should be gathered when just ripe, but before the fruit becomes too soft or pulpy to dry effectively. Spread on trays to dry turning fleshy fruit frequently to ensure even drying. Discard any with signs of mold.
Leaves that are large like burdock, can be gathered individually. Smaller leaves such as lemon balm can be collected on the stem, and separated later. Leaves of deciduous herbs should be gathered just before flowering. Evergreen leaves, like rosemary, can be gathered throughout the year. Sometimes young leaves are collected separately for cooking, soups, salads, and spring tonics, as in the case of nettles or dandelions. A second crop of herbs can then be taken closer to flowering for the more mature leaves. Comfrey leaves can be harvested all summer.
Roots are generally gathered in the autumn when the aerial parts of the plant have died down and before the ground becomes too hard, making digging difficult. Some roots reabsorb moisture from the air and must be discarded if they become soft. Large roots should be chopped into smaller pieces when fresh since they can be difficult to cut when dry.
Sap and resin are collected from the tree in autumn by making a deep incision in the bark or drilling a hole and collecting the sap in a cup tied to a tree. Sometimes a sizeable bucket is needed. A large amount of birch sap, for example, can be collected overnight at certain times of the year. Squeeze sap from such latex plants as wild lettuce over a bowl. Many saps can be corrosive, and wearing rubber gloves is necessary when handling them. For collecting aloe gel, simply cut along the center of the leaf and scrape out the gel.
Seeds should be collected when they start to dry on the plant. With some like Calendula, you can pick off the seeds as they dry. With others like Dill, you can cut the stem, and hang the entire stalk of seed heads upside down over a paper-lined tray or in a paper bag . Seeds will fall into the bag, or onto the tray, when completely dry.