Mountain Alyssum Plant Care

Mountain Alyssum (Alyssum montanum) belongs to the Brassicaceae family within the Alyssum genus. Mountain Alyssum is also known as Rock Madwort.

Mountain Alyssum displays a low spreading ground cover growth habit, reaching up to 0.5 ft tall with a spread of approximately 1.5 ft. Mountain Alyssum produces small clusters of tiny, fragrant white, pink, or purple flowers.

Leaf size: approximately 1 inches.

Water a young or newly planted Mountain Alyssum 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.

Mountain Alyssum thrives in full sun to partial shade.

Alyssum montanum tolerates temperatures of 50–75°F. Mountain Alyssum prefers humidity levels of 40–70%.

Well-draining sandy loam with added organic matter. Good drainage is essential for Mountain Alyssum to prevent waterlogging, which leads to root rot and fungal issues.

Feed Mountain Alyssum every 4 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 sandy loam with added organic matter. Avoid low spots where water collects after rain.

Mountain Alyssum 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.

Mountain Alyssum can spread to about 2 ft (0.5 m) and reach about 1 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 Mountain Alyssum 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.

Mountain Alyssum 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.

Mountain Alyssum can be propagated through seeds. Similar propagation techniques also apply to desert alyssum plant care, which shares the same genus.

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

Mountain Alyssum is susceptible to aphids, cabbage worms, flea beetles. 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.

Mountain Alyssum grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. In cooler regions, grow Mountain Alyssum as a houseplant or bring it indoors before the first frost.