Phyllostegia knudsenii Plant Care

Phyllostegia knudsenii (Phyllostegia knudsenii) belongs to the Lamiaceae family within the Phyllostegia genus. Phyllostegia knudsenii is native to Hawaii.

Phyllostegia knudsenii displays an upright, spreading shrub growth habit, reaching up to 2 ft tall with a spread of approximately 3 ft. Phyllostegia knudsenii produces tubular flowers in shades of purple, pink, or white.

Leaf size: approximately 4 inches.

Water a young or newly planted Phyllostegia knudsenii 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.

Phyllostegia knudsenii thrives in partial shade to full sun.

Phyllostegia knudsenii tolerates temperatures of 60–80°F. Phyllostegia knudsenii prefers humidity levels of 50–70%. A pebble tray or humidifier helps maintain adequate moisture around the plant.

Well-draining loamy soil with added organic matter for moisture retention. Good drainage is essential for Phyllostegia knudsenii to prevent waterlogging, which leads to root rot and fungal issues.

Feed Phyllostegia knudsenii 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 partial shade to full sun and well-draining loamy soil with added organic matter for moisture retention. Avoid low spots where water collects after rain.

Phyllostegia knudsenii is suited to USDA Zone 13a.

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.

Phyllostegia knudsenii can spread to about 3 ft (0.9 m) and reach about 2 ft (1 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 plant spacing calculator.

Prune Phyllostegia knudsenii 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.

Phyllostegia knudsenii 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.

Phyllostegia knudsenii can be propagated through seeds, stem cuttings. Similar propagation techniques also apply to short-toothed phyllostegia plant care, which shares the same genus.

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

Phyllostegia knudsenii is susceptible to aphids, spider mites, whiteflies. 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.

Phyllostegia knudsenii grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Phyllostegia knudsenii is native to Hawaii. In cooler regions, grow Phyllostegia knudsenii as a houseplant or bring it indoors before the first frost.