St. John’s Wort (hypericum perforatum)

St. John’s wort, a perennial, bears bright yellow, five-petaled flowers and red, pink, orange, green, or brown berries. The flower petals have tiny black dots near the margins that give the plant its species name, perforatum.

The common name possibly comes from the plant’s bloom time — around St. John’s Day (June 24) — or from the reddish color of its crushed flowers, symbolizing the saint who is often depicted in a red robe.

For more than 2,000 years, people have used St. John’s wort to treat insomnia, anxiety, and mild depression. The Greek physician Hippocrates (460–377 BCE) was an early proponent of the plant’s therapeutic value.

St. John’s Wort

Plant profile

Common Name: St. John’s Wort

Description: Erect perennial, up to 2 feet tall; spreads by underground runners; small, oblong leaves; bright yellow, flat flowers; turpentine-like smell

Hardiness: To Zone 5

Family: Hypericaceae

Flowering: Midsummer

Parts Used: Flowers

Range/Habitat: Native to Europe, North Africa, and Asia; naturalized in North America in woods, meadows, and along roadsides

Medicinal use

Many scientific studies have confirmed the safety and effectiveness of St. John’s wort for treating mild to moderate depression, along with accompanying fatigue, anxiety, and insomnia. The compound or compounds responsible for the herb’s antidepressant activity are not yet known. Its flowers and unopened buds contain hyperforin (a compound that has antibiotic properties) and hypericin (a substance that gives St. John’s wort oils and tinctures a deep red color). When used externally, St. John’s wort seems to help nerve pain, wounds, burns, and insect bites. It is a common ingredient in skin cleansers, as well as face, body, and hand creams.

Caution: Fair-skinned people using St. John’s wort should avoid excessive exposure to sunlight because this herb can increase sun sensitivity. Talk to your physician or pharmacist before using St. John’s wort if you are taking prescription medications, as the chance for herb-drug interaction is high. Do not use this herb if you are taking prescription antidepressants.

Other uses

The stems can be used to dye alum-mordanted fabric a brownish red. The flowers produce a yellow, orange-red, or mauve dye, depending on the mordant and dyeing method used.

How to grow it

St. John’s wort grows best in full sun and well-drained, fairly dry soil. Plant the seeds or root divisions in spring or fall. St. John’s wort spreads by runners; pull out unwanted plants to control their growth. For medicinal use, cut the flowering stems just as they begin to bloom; use the flowers fresh or dried.

Caution: St. John’s wort can become invasive and can be toxic to cattle if consumed in extremely large quantities.