St. John's Wort

St. John's Wort is a hairless, woody-rooted perennial herb with bright yellow flowers marked by black glands and leaves peppered with translucent oil glands that give them a perforated appearance. Native to Europe and well naturalised across Sweden, it thrives in open, sunny spots and is an extremely hardy, low-maintenance plant. It is valued as a medicinal herb, a dye plant, and a culinary curiosity. One plant can produce thousands of seeds and readily self-seeds once established.

Growing

Sow the tiny seeds very shallowly — no more than 0.2 cm deep — onto a fine, firm seedbed. Seeds require light to germinate (light-germinating), so press them gently onto the surface rather than burying them. Sow direct outdoors or start indoors once soil temperatures reach around 10 °C. Germination takes 10–20 days. Space plants 30 cm apart in all directions. Plants establish slowly in year one and flower strongly from year two onward.

Care

St. John's Wort requires very little attention once established. Water during prolonged dry spells in the first season; mature plants are drought-tolerant. No feeding is necessary on average soils. Cut plants back by one-third after the main flowering flush to encourage a second flush and prevent excessive self-seeding. Remove weeds around seedlings in the first year as the young plants are slow to compete.

Harvest

Harvest flowering tops when the buds are just opening and the majority of flowers are fully open — this is when the active hypericin content is highest. Pinch or cut the top 10–15 cm of flowering stems. The harvest window is around 30 days. A second, lighter harvest may be possible if plants are cut back promptly after the first.

In the kitchen

Young tender leaves can be added sparingly to salads. Flowering tops are used to infuse oils and tinctures, and the dried flowers are a traditional flavouring for aquavit and other spirits. Use the flowers fresh in infused olive oil for topical preparations or steep in warm oil for several weeks in a sunny spot.

Storing

Dry harvested flowering tops quickly in a single layer at low heat (below 35 °C) or in a warm, well-ventilated space out of direct sunlight. Once fully dry, store in airtight dark glass jars for up to 12 months. Infused oils keep for 6–12 months in a cool, dark place. Fresh flowers do not store well and should be processed immediately.