True St John's wort (Hypericum perforatum) is a meadow plant that reaches 40 to 80 cm and flowers yellow from late June into August. The name comes from the flowering falling around St John's Day at midsummer. Hold a leaf up to the light and you see tiny translucent dots, and squeeze a bud between your fingers and they stain red. Those are the two surest identifiers.
Three plants are called St John's wort
This is the first stop, because the species you buy decides what you can do with it.
| True St John's wort | Rose of Sharon | Berried hypericum | |
|---|---|---|---|
| Species | Hypericum perforatum | Hypericum calycinum | Hypericum inodorum |
| Habit | Perennial herb, 40 to 80 cm | Low ground cover, 30 cm | Shrub, 60 to 120 cm |
| Used for | Meadow, tea and oil | Ground cover | Berries in bouquets |
| Identifier | Translucent dots in the leaf | Large flowers, no dots | Red to black berries |
Only the true species has the dots, and it is the one included in our Swedish meadow mix along with twenty-four other native species.
Sowing St John's wort
The seed is very fine, almost like dust, and it needs light to germinate. Scatter it on the surface and press it down, do not bury it.
Winter sow in autumn, in October or November, in a tray outdoors or straight in place. The winter cold lifts germination markedly.
Or cold stratify in the fridge for four weeks and sow indoors in March at 18 to 20 degrees.
Germination takes 10 to 30 days and is uneven.
Plant out 30 cm apart once the seedlings have four leaves.
There is more on the method in our guide to winter sowing, and more species that suit it among our seeds for winter sowing.
Position and soil
Full sun and lean, free-draining soil. St John's wort grows wild on road verges and dry grassland, and it turns thin and floppy in rich garden soil.
Do not feed. Nitrogen gives long stems and fewer flowers.
Water only in the first season. Established it takes drought well.
Lime does no harm. It tolerates pH up to about 7.5.
It spreads both by seed and by short runners. Cut the flower stems before the seed ripens if you want it to stay put.
Harvest at midsummer
Harvest when about a third of the flowers in the cluster are open, usually the first weeks of July. The content of the active compounds peaks then.
Cut the top 20 to 30 cm of the shoots on a sunny morning, once the dew has dried.
Bundle loosely and hang upside down in shade, airy and no warmer than 35 degrees.
After two to three weeks the material is dry and can be rubbed down into a jar.
Store in the dark. Light breaks down the red pigments within a few months.
The red oil
The classic use is St John's wort oil, also called red oil. Fresh flower buds go into a glass jar and are covered completely with cold-pressed olive or sunflower oil. The jar then stands in sunlight for three to six weeks and is shaken every day.
The oil turns deep red from a compound called hypericin. Strain it through a coffee filter and store it dark and cool. Use only dry, fresh buds: water in the jar means mould.
One thing to know before you use it
St John's wort is one of the herbs that changes how the body breaks down medicines. It can reduce the effect of the contraceptive pill, blood thinners and certain antidepressants among others, and that combination can be serious.
If you take prescription medicines, talk to a doctor or pharmacist before taking St John's wort internally. Grow it by all means, but treat it as a medicine rather than a culinary herb.
Grazing animals with pale coats can become light-sensitive from eating large amounts. That is why the plant counts as a weed in some pasture.
Insects and meadow
The flower has no nectar but produces plenty of pollen, and it is visited mainly by bees and hoverflies. In a meadow patch it therefore works best alongside nectar-rich species.
To build an area that flowers all summer there is more advice in our article on perennials and in the one on making a butterfly garden.
Common mistakes
The seed gets buried. It then does not germinate at all. Sow on the surface.
Planted in rich border soil. Gives foliage and few flowers.
Harvested in August. Too late, the levels have dropped.
Dried in the sun. Sun bleaches and destroys the red compounds. Dry in shade.
Seed left to ripen. The plant sows itself across the whole bed.
More meadow species are among our flower seeds.
Author: Emma Vogiatzi
Fact checked by Erik Hoekstra
Last updated 2026-08-31