Mountain St. John's Wort Plant Care

Mountain St. John's Wort (Hypericum montanum) belongs to the Hypericaceae family within the Hypericum genus. Mountain St. John's Wort is native to Eurasia and Morocco in North Africa. Mountain St. John's Wort is also known as St. John's Wort.

Mountain St. John's Wort displays an upright, bushy shrub growth habit, reaching up to 3 ft tall with a spread of approximately 2 ft. Mountain St. John's Wort produces bright yellow, star-shaped flowers with prominent stamens.

Leaf size: approximately 4 inches.

Water a young or newly planted Mountain St. John's Wort 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.

Mountain St. John's Wort thrives in full sun to partial shade.

Hypericum montanum tolerates temperatures of 50–80°F. Mountain St. John's Wort prefers humidity levels of 40–70%.

Well-draining loamy soil with added organic matter for moisture retention. Good drainage is essential for Mountain St. John's Wort to prevent waterlogging, which leads to root rot and fungal issues.

Feed Mountain St. John's Wort 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 loamy soil with added organic matter for moisture retention. Avoid low spots where water collects after rain.

Mountain St. John's Wort is suited to USDA Zone 5a – 8b.

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 St. John's Wort 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 Mountain St. John's Wort 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 St. John's Wort is hardy down to USDA zone 5a, 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.

Mountain St. John's Wort can be propagated through softwood cuttings, seeds. Similar propagation techniques also apply to addington's st. john's wort plant care, which shares the same genus.

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

Mountain St. John's Wort is susceptible to aphids, scale insects, spider mites. 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 St. John's Wort grows outdoors in USDA Zone 5a – 8b. It survives winters down to planting zone 5a. Mountain St. John's Wort is native to Eurasia and Morocco in North Africa.