Sweet William Plant Care

Sweet William (Dianthus barbatus) belongs to the Caryophyllaceae family within the Dianthus genus. Sweet William is native to southern Europe and parts of Asia.

Sweet William displays a compact, mounding habit growth habit, reaching up to 0.5 ft tall with a spread of approximately 0.5 ft. Sweet William produces small, fragrant flowers in various colors like pink, red, white.

Leaf size: approximately 2 inches.

Water a young or newly planted Sweet William 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.

Sweet William thrives in full sun to partial shade.

Dianthus barbatus tolerates temperatures of 50–75°F. Sweet William prefers humidity levels of 40–60%.

Well-draining, slightly alkaline soil with good organic content. Good drainage is essential for Sweet William to prevent waterlogging, which leads to root rot and fungal issues.

Feed Sweet William 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, slightly alkaline soil with good organic content. Avoid low spots where water collects after rain.

Sweet William 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.

Sweet William 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 Sweet William 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.

Sweet William 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.

Sweet William can be propagated through seeds, division, cuttings. Similar propagation techniques also apply to carnation plant care, which shares the same genus.

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

Sweet William is susceptible to aphids, spider mites, 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.

Sweet William grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Sweet William is native to southern Europe and parts of Asia. In cooler regions, grow Sweet William as a houseplant or bring it indoors before the first frost.