Problems With Agapanthus
Agapanthus, commonly called Lily of the Nile, forms a large clump of strap-like leaves. Tall stalks hold large clusters of purplish-blue or white flowers in summer and early fall. Agapanthus can be used as a border plant, in a mixed bed of perennials or in a container.
Failure To Bloom
Plant Agapanthus 2 feet apart in well drained soil in full sun to partial shade. Too much shade causes the leaves of the plant to fall over and decreases the number of blooms. Plants that are crowded will decrease or stop blooming completely. Dig up the plants, divide into two or more separate plants, and replant 2 feet apart.
Slugs and Snails
Slugs and snails hide underneath foliage or mulch during the day and come out at night to eat. They leave ragged edges on the leaves of Agapanthus and if left uncontrolled, will eat the plant to the ground.
There are several ways to control slugs and snails. Use a light at night to find and pick them off plants. Set a bowl of beer with the rim level with the ground - snails and slugs will crawl into it and drown.
The rough texture of diatomaceous earth or crushed eggshells around plants deters slugs and snail. Copper wire or tape around plants mildly discourages slugs and snails by giving them a mild electrical shock. When using a chemical product to control snails and slugs, follow the manufacturer's directions.
Fungal diseases appear on Agapanthus plants during cool and rainy or humid weather. Botrytis affects all parts of the plant except the roots, while Fusarium causes the bulb to rot. Phytophthora and Phythium causes the stems to discolor and the leaves to wilt and die. Eventually the roots will turn black and rot.
There is no chemical treatment for fungal diseases on Agapanthus plants. Use a fungicidal spray according to the manufacturer's directions as a preventative measure. Improve the growing conditions of Agapanthus by providing adequate drainage and spacing. Remove diseased plants and plant parts to stop the spread of disease.