Plants in the genus Ageratum include 40 or so species of annuals, perennials, and shrubs from North and South America. Most are grown as annuals in the garden, and most form dozens of small flowerheads in the form of soft, rounded clusters in summer and fall. They are good choices for edging, bedding, or containers. Noteworthy CharacteristicsClusters of 30 to 50 small flowerheads. Attractive to butterflies. Usually grown as annuals. CareProvide full sun to part shade. Soil should be fertile and moist but well-drained. PropagationIn early spring, sow seed at 61° to 64°F. Or, sow in autumn and overwinter at 50°F.ProblemsSouthern blight, crown rot, root rot. During cool, wet weather Botrytis blight may affect plants, while rust and powdery mildew can be problems in dry summers.