Welsh Onion Plant Care

Welsh Onion (Allium fistulosum) belongs to the Amaryllidaceae family within the Allium genus. Welsh Onion is native to China. Welsh Onion is also known as Japanese Bunching Onion, Scallion, Green Onion.

Welsh Onion displays a clumping, upright growth habit, reaching up to 1 ft tall with a spread of approximately 0.5 ft. Welsh Onion produces ivory-white, globular.

Leaf size: approximately 10 inches.

Water a young or newly planted Welsh Onion every 3–7 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.

Welsh Onion thrives in full sun.

Allium fistulosum tolerates temperatures of 50–80°F. Welsh Onion prefers humidity levels of 40–60%.

Well-draining. Good drainage is essential for Welsh Onion to prevent waterlogging, which leads to root rot and fungal issues.

Feed Welsh Onion every 12 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 and well-draining. Avoid low spots where water collects after rain.

Welsh Onion is suited to USDA Zone 4a – 9b.

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.

Welsh Onion can spread to about 1 ft (0.2 m) and reach about 1 ft (0 m) tall. Space plants about 1 ft (0.2 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 Welsh Onion 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.

Welsh Onion is hardy down to USDA zone 4a, 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.

Welsh Onion can be propagated through seeds or division. Similar propagation techniques also apply to garlic plant plant care, which shares the same genus.

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

Welsh Onion is susceptible to onion thrips, onion maggots. 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.

Welsh Onion grows outdoors in USDA Zone 4a – 9b. It survives winters down to planting zone 4a. Welsh Onion is native to China.