Cosmos are effective nectaries for butterflies and can be planted to attract pollinators and other beneficial insects such as syrphid flies, lacewings and parasitic wasps. Cosmos are also said to repel the corn earworm. As a companion plant, scatter seeds at plot edges, or plant at intervals within garden. It is a warm-weather annual that tends to reseed itself. Highly adaptable to a wide variety of conditions.
Plant in well-drained soil in full sun to partial shade. Seeds can be covered 0.6cm (¼ inch) since they do not need light to germinate. Germination will usually occur in just 3 to 5 days, but it can take up to 2 weeks. Tolerant of low fertility. Will become leggy if soil is too rich. Prefers neutral to alkaline pH.