Giant milkweed Plant Care

Giant milkweed (Dolichometra leucantha) belongs to the Rubiaceae family within the Dolichometra genus. Giant milkweed is native to the East Usambara Mountains in Tanzania. Giant milkweed is also known as White-flowered cotton bush.

Giant milkweed displays a tall, upright shrub growth habit, reaching up to 5 ft tall with a spread of approximately 3 ft. Giant milkweed produces small, white fragrant flowers in clusters.

Leaf size: approximately 4 inches.

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

Giant milkweed thrives in bright indirect light. Avoid placing Giant milkweed in direct, harsh sunlight for extended periods, as this can scorch the foliage.

Dolichometra leucantha tolerates temperatures of 65–80°F. Giant milkweed prefers humidity levels of 50–70%. A pebble tray or humidifier helps maintain adequate moisture around the plant.

Rich, well-draining soil with high organic content. Good drainage is essential for Giant milkweed to prevent waterlogging, which leads to root rot and fungal issues.

Feed Giant milkweed every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees 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 bright indirect light and rich, well-draining soil with high organic content. Avoid low spots where water collects after rain.

Giant milkweed is suited to USDA Zone 13b.

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

Giant milkweed can spread to about 3 ft (0.9 m) and reach about 5 ft (2 m) tall. Space plants about 3 ft (0.9 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 tree spacing calculator.

Prune Giant milkweed 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 tree in one year.

Giant milkweed is frost-tender (hardy to USDA zone 13). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Giant milkweed can be propagated through seeds, stem cuttings.

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

Giant milkweed is susceptible to aphids, spider mites, scale insects. 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.

Giant milkweed grows outdoors in USDA Zone 13b. It survives winters down to planting zone 13b. Giant milkweed is native to the East Usambara Mountains in Tanzania. In cooler regions, grow Giant milkweed as a houseplant or bring it indoors before the first frost.