The agapanthus, also known as the lily of the Nile or African lily, is a perennial that originated in South Africa. Agapanthus forms large clumps of bulbs that eventually produce dense stands of colorful flowers. They are often used for borders, containers or in rock gardens. While agapanthus are considered easy to grow, many gardeners report having problems making them bloom. There are recommended solutions.
Lack of Sunlight
Agapanthus like lots of sun. If they're not blessed with a bright, sunny location, they won't flower well. They should have at least a half day of sun. If possible, plant them so they face south and get more sun, not the north where they will likely spend more time in the shade.
Containers Versus Outdoors
Agapanthus are hardy and vigorous outdoors, but don't do so well in a container. If you have a bed or border that is protected from the most bitter winter winds, you should move them there.
If you grow your agapanthus in a container, you likely water them more frequently than if they are planted in the ground. This tends to leach out the nutrients in your potting soil, so you should use more fertilizer.
If you don't fertilize your agapanthus the first year, it might not bloom. To encourage blooming, use a 10-20-20 fertilizer (10 parts nitrogen by weight and 20 parts each of phosphorus and potassium). Phosphorus encourages blooming.
Use water-soluble, quick-release fertilizer every two weeks during the growing season or slow-release fertilizer once during the growing season. Follow the directions on the label for organic fertilizers.
Reports from gardeners are mixed on the issue of whether or not to divide and repot agapanthus. Some gardeners stick with the traditional wisdom that dividing and replanting encourages blooming of perennials. However, most gardeners are reporting that agapanthus thrive better and produce blossoms when their roots are crowded. You should wait for three years or more before you divide the roots.
A young bulb may not produce flowers the first year. Move your plant from a pot to the ground. Agapanthus are terrific growers and will spread by themselves. Make sure your plant has plenty of sun. Nourish it with a fertilizer that contains lots of phosphorous. It should eventually bloom.