Stevia (Stevia rebaudiana 'Bertoni') is native to South America, where the plant's leaves have been used for centuries as a sweetener. You can grow stevia in your home garden. Plants grow best in full sun in loamy soil with good drainage. Avoid poorly drained areas. Start with transplants from a reliable nursery or garden center. Plants grown from seed vary in their level of sweetness, so vegetatively propagated ones are best. Plant outdoors after all danger of frost has passed. After planting, cover lightly with organic mulch to hold down weeds and conserve moisture. Water during dry periods, and use fertilizer low in nitrogen on the plants. Harvest stems for drying in fall. The cooler temperatures and shorter days of fall intensify the sweetness in the leaves. Cut stems from the plant; strip the leaves and dry them on a screen in a sunny spot with good ventilation. Take cuttings in late summer to carry over plants for the next year. Pot up the rooted cuttings and move them indoors before fall frosts arrive. Keep plants inside in a sunny location through the winter, and plant them outside the following spring.