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Common St John’s Wort (Hypericum Perforatum)


The Common St John’s Wort plant (scientific name Hypericum perforatum), a yellow wildflower, is a perennial plant which grows to between one and three feet tall. It thrives in many landscapes, including farmland, woodland, pastures and gardens. The plant can be found across Europe, where it is a native species, and further afield in Canada, the USA, Australia and South Africa.

Common St John’s Wort grows very easily; so much so it sometimes suffers a reputation for being a nuisance, noxious weed. It can also, in very large doses, be poisonous if consumed by livestock.

At Turfonline, however, we view Common St John’s Wort as a thriving wildflower, the RHS see it as a ‘Perfect for Pollinators’ plant and, with its bright yellow flowers which bloom during summer, it adds colour to a patch of wildflower meadow. It is also known for its many health-giving properties (more of which below).

How to grow and harvest Common St John’s Wort

Planted in spring, in mild temperatures and after the last frost, Common St John’s Wort is a hardy plant that will grow in most types of soil. It is a nectar source for pollinators so will provide both colour and a purpose during the summer months.

If you plan to harvest it, allow it to flower first. Bunch the stems together and hang in a cool, dry place, to let the leaves and flowers dry out – this process should take around two weeks. If you do decide to grow Common St John’s Wort, keep an eye on it, as it spreads quickly and can overwhelm other plants and herbs. One option is to grow it on its own in a pot or window box.

Traditional uses for Common St John’s Wort

St John’s Wort has been used for medicinal purposes since ancient Greek times; there is even a record of Hippocrates noting the benefit of the flowers.

Thanks to the chemical compounds present in the leaves of Common St John’s Wort, over the past few decades the plant has become recognised as an effective treatment for mild to moderate depression, as well as related conditions such as anxiety, tiredness, insomnia and loss of appetite.

An oil can be made from the flowers of Common St John’s Wort, which has anti-inflammatory qualities and is used to treat cuts, ulcers, wounds and muscle pain.

The flowers can also be used for a herbal tea that some people drink to treat bladder problems and diarrhoea.