Agapanthus, also called Lily of the Nile, grows 12 to 60 inches tall and blooms in the summer with clusters of white, blue or pink trumpet-shaped flowers. You can plant this exotic flower as a perennial in USDA zones 8 and above, where the temperature does not drop below 20 degrees Fahrenheit. Some hybrid cultivars, however, can survive in USDA zone 7. Knowledge of how to create the right environment for this flower will help you produce a healthy and attractive plant.
Choose an area to plant the agapanthus corms in spring, after the danger of frost passes. This plant prefers full or half sun and well-drained soil rich in organic material. Before planting, mix in 1 to 2 inches of organic compost 6 to 8 inches into the soil to increase fertility.
Plant agapanthus corms 1 to 2 inches deep and space them 18 to 24 inches apart. Do not allow the corms to dry out before they start to grow vigorously or they may not grow at all.
Water the agapanthus during the growing season, keeping it continually moist. Once the plant is established it can tolerate drought, but for the best health do not allow it to dry out during the growing season.
Fertilize the agapanthus with a complete fertilizer marked 10-20-20, especially right before bloom. The numbers mean the fertilizer consists of 10 percent (by weight) nitrogen, 20 percent phosphorus and 20 percent potassium (as well as other elements that make up the rest). The phosphorus will encourage blooming. Follow the directions on the package for application instructions.
Reduce watering and stop fertilizing in late fall. This will allow the plant to go dormant. Continue to water through the winter, allowing the plant to dry completely between waterings.