Stevia is part of the aster family, which encompasses 21,000 species worldwide, including dahlias, sunflowers, marigolds and zinnias. The flowers of aster family have a composite inflorescence, in which a ring of elongated ray flowers surrounds a cluster of small disk flowers. The leaves of the stevia plant are dried and used as a sweetener, which is an alternative to cane sugar. Although the plant is native to South America, gardeners around the world have grown it with success for a long time.
The best way to start a stevia plant is to purchase a starter plant from a greenhouse, according to Stevia.net. Transplant the stevia plants into an area that has plenty of sun and well-drained soil, after the threat of frost has passed. Place stevia plants in rows with 18 inches between plants and 20 to 24 inches between rows.
Water the stevia plants once or twice a week and apply a fertilizer when the plants begin to grow. Stevia.com recommends using an organic or low-nitrogen fertilizer one month after transplant. Additionally, as the weather heats up, protect the roots of the stevia plant by applying organic compost around the base to keep them moist. Pinch the plant every three to four weeks, which means to cut the main stems to encourage the plant to branch out, to protect it from high winds. The plant is highly pest resistant, but is susceptible to fungus if planted in poorly drained soil.
To harvest a stevia plant, pick all of the leaves, take them inside and dry them by spreading them on paper plates or newspaper until the leaves crumble to the touch, suggests Rose Marie Nichols McGee and Maggie Stuckey in their book, "McGee & Stuckey's Bountiful Container: Create Container Gardens of Vegetables, Herbs, Fruits, and Edible Flowers." Grind the leaves into a powder with a coffee grinder and store in an air-tight glass container. This stevia powder can be used to sweeten food and drinks.