Perennial.
Thrives in poor to average soil. Likes full sun or part shade. When planting seeds, just press them into the ground, don't cover them with soil. Can be propagated by cuttings.
Thought to ward off witches and fairies. A sprig was hung above a picture to repel evil spirits.
The red oil extracted from the flowers was used externally to treat burns, neuralgia, hard tumors, caked breasts, bruises, and sciatica. Taken internally for cancer, rabies, gout, arthritis, respiratory and gastrointestinal ailments, menstrual cramps, nervous disorders, insomnia, and depression. Said to be used for bedwetting.
The Cherokee used this herb to reduce fever, promote menstruation, and treat diarrhea, nosebleed, venereal disease, and snakebite. They washed their babies with an infusion of the roots to make them strong.
Dried or fresh flowers can be used for an infusion to treat insomnia and bedwetting. It is also used to treat bronchitis and coughs and upset stomach.
A decoction of the seeds is good for palsy, and fevers. "Trefoil, Johnswort, Vervaine, Dill, hender witches of their will."
The festival of St. John the Baptist occurs on June 24th, when the sun is high and days are long. The bright flowers of St. Johnswort open about this time in England, and so, as the ancient couplet indicates, they came to embody the power of light over darkness.
The plants actually contain a most unusual toxin. Eaten in the flowering stage, they sensitize nerve endings in the skin and cause inflammation and open sores in light skinned annimals and humans exposed to sunlight. Dark skins are seldom affected, and light skins are immune if they are kept shaded.