Nonetheless, people can buy stevia powder and use it in place of sugar at home. The substances responsible for the plant's sweetness are chemicals called glycosides, primarily one dubbed stevioside, which are concentrated in the leaves. These and other related chemicals are at their peak just before flowering, which is triggered by the shorter days of late summer and early fall. In the wild, the plant grows in infertile, moist, sandy soil near streams and marshes. The pretty flowers are tiny and white with a pale purple throat, but they must be pinched off or they will steal sweetness from the leaves.
Stevia likes heat and can be grown as a perennial in frost-free areas.
Elsewhere, the best approach is to treat it as an annual herb such as basil. For best results, plant stevia in the garden for the summer, harvest the fresh leaves before flowering, and dry them for later use. Transplants can be ordered from a mail-order nursery in the spring and planted in the ground when the soil temperature reaches about 65F. A sandy loam with a slightly acid to neutral pH and good drainage is important. If your soil is heavy clay or otherwise slow-draining, plant in a raised bed or container filled with lightweight soil mix. Stevia has a temperamental nature that is often reflected in slow growth when the plants are first set out.