Alternanthera is the botanical genus name for any of 200 different species of tropical annuals and perennial herbs native to tropical parts of Central and South America. These plants have common names like calico plant and Joseph's coat. Plant alternantheras as summer annuals to bring their colorful leaves and sprawling growth habits to flower beds, hanging baskets and containers. Even though alternantheras produce flowers, they're tiny but yield seeds for sowing. Seedlings are variable in their leaf color and habits, so consider stem cuttings to overwinter plants indoors and create additional plants.
Locate a prime growing spot in your garden for the alternanthera plant. To grow well without the threat of fungal diseases, consider planting it only where the soil is moist but well-draining. Both clay and sandy soils need organic matter incorporated to make them crumbly and more suitable. Alternanthera plants need abundant light to maintain their leaf coloration, so the garden site must receive at least 4 to 6 hours of direct sunlight daily.
Sow seeds of alternanthera where they are to grow in the garden when there is no threat of frost and the soil temperatures are between 55 and 65 degrees F, advises the American Horticultural Society's "A-Z Encyclopedia of Garden Plants." Alternatively, transplant seedling from a nursery to the garden after the thread of frost has passed.
Supplement natural rainfall if the soil around the alternanthera plants doesn't remain evenly moist. Avoid dry soils and soggy, wet soil conditions. It is common for plants to wilt somewhat even in moist soils in the heat of the midsummer afternoon. They recover once temperatures drop in the evening.
Cut back wiry stems with a scissors, hand pruners or pruning shears as needed to maintain more compact plants. Don't worry, alternanthera species recover after pruning, often with more branching and a renewed vigor and more colorful stems and foliage.