Hypericum Perforatum Plants

• Hypericum perforatum is commonly known as St. John's wort. Teas, liquid extracts and capsules made from its leaves and flowers are often sold as an over-the-counter herbal supplement for treating depression. Although it's a naturally occurring, wild herb used by humans for medicinal purposes, Ohio State University lists it as a poisonous plant for livestock. It is dangerous to animals at every stage of life, and even after, should plant parts get mixed into hay or feed. In humans, overexposure to the plant's leaves, roots and flowers can cause skin rashes, photosensitivity, vision problems and even coma.

Propagation

• Hypericum perforatum is a perennial, and reproduces through flower pollination and seeding. After pollination occurs, a small, green fruit develops when the flower petals fall. Later in the season, this three-celled fruit turns brittle. Break one open and you'll find dozens of tiny, brown seeds. This plant can also spread through underground, running roots, sending up new shoots from small nodules.

Growth Habit

• Hypericum perforatum can grow up to 3 feet tall in a season. Tough, woody stems have opposing, pale green, oval leaves. Hold one up to the light, and you'll see small perforations, called stomata. Its flowers are bright yellow with black dots on the petal margins, and about 1 inch in diameter. A bushy, creeping growth habit and profuse flowering help it spread rapidly without much help.

Cultural Requirements

• Hypericum perforatum requires very little cultivation from humans. It occurs naturally in old pastures, farmland, ditches and roadsides. If you want to grow it at home, Virginia Tech recommends moist soil and full sun. Broadcast the tiny seeds by hand on top of the soil, then cover with 1/4-inch of dirt. Thin seedlings to 12 inches apart to avoid overcrowding.