How to Care for Alternanthera
Known as Joseph's coat, calico plant, copperleaf and by many other common names, alternanthera (Alternanthera spp.) is a genus of tropical perennial plants in the Amaranthaceae family that are grown for their strikingly colorful foliage. There are many cultivars available that feature a range of color combinations.
Alternanthera are low-maintenance plants hardy in U.S. Department of Agriculture zones 9 to 11.
Types of Alternanthera
One of the most common species of alternanthera is Alternanthera dentata, which is native to the West Indies and is hardy in zones 10 and 11. This species has heights of about 3 feet. Species plants have green leaves, but cultivars with purple and burgundy foliage are more commonly available. Purple Knight (Alternanthera dentata 'Purple Knight') is a popular cultivar.
Some of the low-growing species and cultivars of alternanthera can be used as ground cover, including Alternanthera ficoidea, which has maximum heights of a foot and is hardy in zones 10 and 12. There are multiple cultivars available, including True Yellow (Alternanthera ficoidea 'True Yellow'), which has chartreuse-colored foliage. If you are looking for a red alternanthera, Red Carpet (Alternanthera ficoidea 'Red Carpet') has crimson-colored leaves.
The Brazilian joyweed (Alternanthera brasiliana, zones 9 to 11) has greenish purple or purple leaves, but this species has become a noxious weed in some parts of the world, including some regions of the U.S. The Brazilian joyweed produces white flowers, although it rarely blooms when it is cultivated as an annual.
Alternanthera Plant Culture
While it is technically a perennial, outside of its hardiness range alternanthera is more commonly grown as an annual. This type of plant works well for bedding.
If you are growing alternanthera plants from seed, you may want to start them indoors and transplant them into the garden once the threat of frost has passed.
Alternanthera plants can also be propagated using cuttings taken from the previous year's plants and overwintered indoors. Some cultivars of alternanthera can be found at nurseries in cell packs.
Alternanthera plants grow best in well-draining soil that contains organic matter but is not overly fertile. Amending the soil with a balanced fertilizer at planting time is usually all the feeding these plants require, though you can apply fertilizer every other month to enhance established plants.
The foliage colors are most vibrant when the plants are grown in full sun. However, some shade during the hottest parts of the day is beneficial, as too much sun can cause bleaching of the leaves. If you can provide enough light, many alternanthera plants can also be grown indoors as houseplants.
Alternanthera Plant Care
Alternanthera plants need even moisture to look their best. For optimum results, avoid letting the soil dry out completely. Apply mulch to keep the soil moist and to discourage weed growth.
Alternanthera plants benefit from pinching, which means removing parts of stems to encourage the growth of two stems above the cut. This gives plants a bushier and denser appearance.
While these plants are not prone to many diseases or pest infestations, spider mites can become an issue in dry weather. Caterpillars may also be a concern.
- Missouri Botanical Garden: Alternanthera ficoidea
- Missouri Botanical Garden: Alternanthera dentata
- Missouri Botanical Garden: Alternanthera brasiliana 'Purple Prince'
- NC State Extension: Alternanthera ficoidea
- University of Florida IFAS Extension: Plant Profiles - Alternanthera
- LSU AgCenter: Little Ruby Alternanthera
Since beginning her career as a professional journalist in 2007, Nathalie Alonso has covered a myriad of topics, including arts, culture and travel, for newspapers and magazines in New York City. She holds a B.A. in American Studies from Columbia University and lives in Queens with her two cats.