Grey Mint Bush Plant Care

Grey Mint Bush (Prostanthera incana) belongs to the Lamiaceae family within the Prostanthera genus. Grey Mint Bush is native to south-eastern continental Australia.

Grey Mint Bush displays an upright, bushy shrub growth habit, reaching up to 3 ft tall with a spread of approximately 2 ft. Grey Mint Bush produces small, tubular flowers in shades of purple, pink, or white.

Leaf size: approximately 2 inches.

Water a young or newly planted Grey Mint Bush every 7–14 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.

Grey Mint Bush thrives in full sun to partial shade.

Prostanthera incana tolerates temperatures of 50–80°F. Grey Mint Bush prefers humidity levels of 40–70%.

Well-draining, slightly acidic soil with added organic matter like compost or peat moss. Good drainage is essential for Grey Mint Bush to prevent waterlogging, which leads to root rot and fungal issues.

Feed Grey Mint Bush 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 acidic soil with added organic matter like compost or peat moss. Avoid low spots where water collects after rain.

Grey Mint Bush 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.

Grey Mint Bush can spread to about 2 ft (0.6 m) and reach about 3 ft (1 m) tall. Space plants about 2 ft (0.6 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 Grey Mint Bush 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.

Grey Mint Bush 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.

Grey Mint Bush can be propagated through softwood cuttings, semi-hardwood cuttings. Similar propagation techniques also apply to mint bush plant care, which shares the same genus.

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

Grey Mint Bush 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.

Grey Mint Bush grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Grey Mint Bush is native to south-eastern continental Australia. In cooler regions, grow Grey Mint Bush as a houseplant or bring it indoors before the first frost.