Herb Harvesting - When to Pick

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.
— Macer's Herbal (16th Century) Quoted by Mrs Grieve (1931): https://www.botanical.com/botanical/mgmh/m/marigo16.html

When perusing 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 (see Biodynamic gardening for answers). Other herbals refer to picking on a holy day such as St John's Wort being picked on its name sakes day. This would probably guide simpler working people without the benefits of a calendar who's lives were guided by the church and knew holy days as significant events. It would make an interesting research study.

On our walks and workshops we are after asked when the best time to pick herbs are. This is an important consideration as we want to pick herbs when they are at their peak in terms of vitality and phyto-chemical profile (plant goodness). So here is a very simple and easy to follow 'rule of thumb' guide for picking various plants throughout the year:

 

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 and vibrant. Spring greens (link) especially such as Cleavers (Galium aparine), Nettle (Urtica dioicia) 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 its highest.

 

Flowers

Flowers are best picked when they are in full bloom, just as they begin to open and before they start to wilt. Always pick flowers on a dry and sunny day as rain can wash away much of their precious nectar and pollen. Certain plants are traditionally picked on a certain day of the year that usually corresponds to a holy day of some kind. St. John's Wort for example is picked near Summer Solstice (21st-22nd June) or St. John's day (24th June). 

 

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, leave a section of the root in the ground.

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. This is when 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.

 

Fruits 

Soft fruits are usually ready to pick in mid-late summer (August) through to early winter (November/December). 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 and Rosehips can be left on the plant until the frosts come, after which the fruits will be considerably sweeter. 

 

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 main them easy to collect. There are a few seeds that are best picked green, such as milky Oat (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. Taking bark from the trunk will undoubtedly kill the plant. Often the bark is taken after the Autumn leaf drop, but before the new buds 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.