Stevia (Stevia rebaudiana) is a relative of the sunflower, and does well in Arizona and other southwestern states. The leaves of the stevia plant are are 20 to 30 times sweeter than refined sugar, according to master gardeners at Washington State University. The stevia plant requires warm, dry days to grow to its full height of 18 inches. The higher the temperature, the sweeter the leaves–so plant stevia in the warmest part of your garden. The best time to plant in Arizona is late March.
Prepare the planting bed by adding a 3-inch layer of compost and a 3-inch layer of sand to the existing soil. Use the gardening fork to mix the amendments to a depth of 8 inches.
Dig a hole in the soil twice the width and the same depth as the pot in which the stevia is growing. Remove the stevia plant from its pot, place the roots into the hole and pack the soil around the plant. If you are planting more than one stevia plant, place them 10 to 12 inches apart.
Water just enough to keep the soil evenly moist. During hot, dry Arizona summers you may need to water every day.
Remove any flowers that appear by pinching them off with your fingers. Pinch the tips of each branch once a week for the first three weeks of planting. This will encourage the stevia plant to produce more branches.
Fertilize the stevia plant with 10-10-12 fertilizer, sprayed on the leaves, 30 days after planting and then again in 30 days. Always water before applying fertilizer. The best time of day to apply fertilizer in your Arizona garden is very early in the morning. Fertilizing during the hottest part of the day may harm the plants.
Inspect the plant for common stevia pests in Arizona, such as aphids and mealy bugs. Insecticidal soap will help manage these pests.