Stevia has been used as an herbal sweetener since ancient times. Its leaves contain compounds called stevivol glycosides, which are 300 times sweeter than sugar says the Washington State University Extension . Remarkably, stevia does not contain calories and does not raise blood sugar levels, making this herb a valuable addition to your garden.
Seedlings vs Seeds: Purchase seedlings at your local greenhouse, as this herb does not germinate well and may take nearly a month to sprout. Otherwise, sow seeds inside at least eight weeks before the last expected frost in your area. In southern areas with long growing seasons, stevia can be direct sown in the garden in late spring once the soil warms.
Soil: Till the soil to a depth of eight to 8 to 12 inches and remove rocks, roots and other debris. Amend with a two to three inch layer of compost or well-rotted manure and mix it into the top six inches of soil. Stevia prefers fertile, well-drained soil.
Location: Choose a location in full sun or partial shade. Full sun typically refers to an area that receives six to eight hours of direct sunlight a day, whereas partial shade may receive four to six hours of direct sunlight or receive filtered light for the majority of the day.
Watering: Stevia produces shallow roots and requires even moisture. Observe plants for signs of wilting and water whenever the soil feels dry to the touch. Avoid soggy soil as this prevents roots from receiving the oxygen they need to thrive.
Pinching: Pinch the growing tips of stevia plants every two to three weeks to create dense, compact foliage and promote healthy growth.
Harvesting: Stevia leaves can be used fresh to sweeten tea or desserts, but have the most intense flavor after drying.
Drying: Pick stevia leaves late in the fall – but before frost threatens – when the flavor has intensified. Bundle the stems together and hang them upside down in a warm, dry, well-ventilated area to dry.
Storage: Once the leaves are dry, crumble them by rolling them between the palms of your hands or crush them with a coffee grinder or the blender. Place the crushed leaves in an airtight container and store them in a dry, dark area.
Liquid Sweetener: To make liquid sweetener from crushed stevia leaves, steep ¼ cup of leaves in one cup of warm water for 24 hours. Strain the mixture and store in the refrigerator.