Greater Water-plantain Plant Care

Greater Water-plantain (Damasonium alisma) belongs to the Alismataceae family within the Damasonium genus. Greater Water-plantain is native to Europe, Asia. Greater Water-plantain is also known as Star-shaped Water-plantain, Alisma damasonium.

Greater Water-plantain displays an aquatic or marsh plants growth habit, reaching up to 1.5 ft tall with a spread of approximately 1.5 ft. Greater Water-plantain produces small white flowers in clusters.

Leaf size: approximately 6 inches.

Water a young or newly planted Greater Water-plantain every 2–4 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.

Greater Water-plantain thrives in full sun to part shade.

Damasonium alisma tolerates temperatures of 50–80°F. Greater Water-plantain prefers humidity levels of 60–80%. A pebble tray or humidifier helps maintain adequate moisture around the plant.

Rich, loamy soil with good moisture retention. Good drainage is essential for Greater Water-plantain to prevent waterlogging, which leads to root rot and fungal issues.

Feed Greater Water-plantain 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 part shade and rich, loamy soil with good moisture retention. Avoid low spots where water collects after rain.

Greater Water-plantain is suited to USDA Zone 8a – 10b.

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.

Greater Water-plantain can spread to about 2 ft (0.5 m) and reach about 2 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 Greater Water-plantain 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.

Greater Water-plantain is hardy down to USDA zone 8a, so once established it can stay outdoors through winter in that zone and warmer ones.

Water deeply in late autumn before the ground freezes, and spread a 5–8 cm (2–3 in) layer of mulch over the root zone, keeping it away from the trunk.

Young and container-grown shrubs need extra protection: roots in a pot freeze much more easily than roots in the ground.

Greater Water-plantain can be propagated through seeds, division of rhizomes. Similar propagation techniques also apply to star-fruit plant care, which shares the same genus.

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

Greater Water-plantain is susceptible to aphids, snails, slugs. 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.

Greater Water-plantain grows outdoors in USDA Zone 8a – 10b. It survives winters down to planting zone 8a. Greater Water-plantain is native to Europe, Asia.