Stevia rebaudiana, the Sweet Leaf. Start transplants indoors 10 to 12 weeks before setting out after the last frost date. Sow seeds on top of soil mix, leaving the seeds uncovered but pressed firmly onto the soil surface, as light aids germination. Provide even moisture, warmth and strong light. Cover with plastic wrap until sprouts emerge: then discard plastic. When seedlings are 4'' tall, harden them off by gradually acclimating them to the outdoors for 1 to 2 weeks. Carefully transplant out into well-draining, loamy soil in full to filtered sunlight spaced 12" to 14" apart. The sweet glycoside-packed leaves may be plucked at any time, but they are best harvested when the plant is in full bloom with dainty white flowers. Height: 24-30".