Where it grows wild, Hypericum spreads by means of underground rhizomes and produces up to 100,000 seeds per plant. No species of Hypericum is considered endangered or threatened, or likely to become so. Cech's company, Horizon Herbs, also sells seed. The booklet provides details of propagation, plants per acre, pests, yields, harvest, storage, and shipping for commercial producers. Sturdivant and Blakley provide further information on propagation, cultivation, harvesting of flowering tops, processing, and selling the herb.
Seeds require strong light to germinate.
Commercial growers in France replace plants every two years. Dealers have their established sources of supply and will buy from newcomers only in an emergency. Price depends on hypericin content, confirmed by analysis of a sample. St. Johnswort is not well adapted to the types of products made by small home herb businesses. AHPA has sponsored symposiums on growing St. Johnswort.