When to pick your medicinal herbs
“It must be taken only when the moon is in the Sign of the Virgin and not when Jupiter is in the ascendant, for then the herb loses its virtue. ”
When reading old Herbals, it is not uncommon to come across belief that certain herbs should be picked at certain times, like the above quote. Perhaps this refers to when the moon would affect the sap rising or sinking, and therefore making the herbs more medicinally valuable (explore biodynamic gardening if you are interested in this). Other herbals refer to picking on a holy day such as St John's Wort being picked on its namesake day.
On our walks and workshops we are often asked when the best time to pick herbs are. This is an important consideration as herbs should be gathered when they are at their peak in terms of vitality and phytochemical profile.
Here is a very simple and easy to follow 'rule of thumb' guide for picking various plants throughout the year, there are always exceptions, but is a good general guide:
Leaves
Although many leafy plants can be picked throughout the growing season, they are at their best in spring and early summer when they are still young, fresh and vibrant. Spring greens such as cleavers (Galium aparine), nettle (Urtica diocia) and dandelion (Taraxacum officinale) are best used early in the spring before they flower. Always pick aromatic herbs on a dry, sunny day as their constituents, particularly those with the aromatic volatile oil content will be at their highest.
Flowers
Flowers are best picked when they are just coming into full bloom, as half are open and half are in bud. This means you get them before they start to wilt and go over. Always pick flowers on a dry and sunny day as rain can wash away much of their precious nectar and pollen.
Roots
Autumn is the best time to harvest roots, as the arial parts of a plant die back, it sends its energy down underground into root storage for overwinter. You can dig up roots at anytime during the year but autumn is when they are at their most potent. Try to harvest roots before the frost comes as the cold makes them very difficult to lift from the soil. Also remember that many plants can be propagated through root cuttings, if you would like your plant to grow back next year, dig it up, harvest the end of the roots, and replant the root crown.
Some plants, such as Burdock (Arctium lappa) are biennials. This means they grow over a two year period. Roots are best harvested at the end of the first Summer/Autumn. I.e. the year they don’t flower. At this point, they have spent a year putting out leaves and collecting food to store in a big root ready for the flower/seed making the next year. The second year, the root will have withered or be less potent.
Fruits
Soft fruits are usually ready to pick in mid-late summer (from July/August). Softer fruits such as blackberries and raspberries are best picked as soon as the ripen as they are prone to fungal infection and rot especially in wet weather.
Harder fruits such as hawthorn berries can be left on the plant until a little later, from September. Some hard fruits are traditionally picked after the first frost, which makes them much sweeter and richer. Examples include rosehips and sloes.
Seeds and Nuts
Nuts from trees such as Hazel and Cobnuts should picked as soon as they are ripe as you will have a race to beat the squirrels.
When harvesting for food and medicine, seeds need careful attention to determine the right time for collecting. You want them to be ripe, not too green and unformed but not too ripe and brown that they begin to drop form the plant and fall to the ground. An easy way to harvest seeds is to chop the seed head off the plant, tie a paper bag around the stem of the plant and hang upside-down. As the plant dries out it will drop its seed into the bag making them easier to collect. There are a few seeds that are best picked green, such as milky oat seed (Avena sativa) and nettle seed which we like to pick when green and ripe, we snip off the seed heads and use them fresh in infusions and tinctures.
Barks
Barks should always be taken from the branches or saplings. Taking bark from the trunk in large amounts will weaken or kill the plant. Often the bark is taken after the autumn leaves drop off, but before the new buds have formed. This means it is easier to strip the bark from the branch without growth-bits getting in the way. Generally a dry day is best as this will reduce the likelihood of mould growing.