Purple Ageratum Plant Care

Purple Ageratum (Deinandra conjugens) belongs to the Asteraceae family within the Deinandra genus. Purple Ageratum is native to a small section of far northern Baja California in Mexico, its range extending north into San Diego County, California, in the United States. Purple Ageratum is also known as Purple Eupatorium, Hemizonia conjugens.

Purple Ageratum displays a low spreading groundcover growth habit, reaching up to 0.5 ft tall with a spread of approximately 1.5 ft. Purple Ageratum produces small daisy-like flowers in various colors.

Leaf size: approximately 2 inches.

Water a young or newly planted Purple Ageratum every 7–10 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established shrubs mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Purple Ageratum thrives in full sun to partial shade.

Deinandra conjugens tolerates temperatures of 50–80°F. Purple Ageratum prefers humidity levels of 40–70%.

Well-draining sandy soil mix with added organic matter. Good drainage is essential for Purple Ageratum to prevent waterlogging, which leads to root rot and fungal issues.

Feed Purple Ageratum every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established shrubs in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with full sun to partial shade and well-draining sandy soil mix with added organic matter. Avoid low spots where water collects after rain.

Purple Ageratum is suited to USDA Zone 12a.

Plant container-grown or balled-and-burlapped shrubs in spring or early autumn, setting the root flare at soil level, and water well after planting.

Purple Ageratum can spread to about 2 ft (0.5 m) and reach about 1 ft (0 m) tall. Space plants about 2 ft (0.5 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the plant spacing calculator.

Prune Purple Ageratum while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the shrub in one year.

Purple Ageratum is frost-tender (hardy to USDA zone 12). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Purple Ageratum can be propagated through seeds, division of root ball. Similar propagation techniques also apply to clustered tarweed plant care, which shares the same genus.

See all plants toxic to cats and plants toxic to dogs.

Purple Ageratum is susceptible to aphids, whiteflies, spider mites. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

Purple Ageratum grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Purple Ageratum is native to a small section of far northern Baja California in Mexico, its range extending north into San Diego County, California, in the United States. In cooler regions, grow Purple Ageratum as a houseplant or bring it indoors before the first frost.