Black Mullein Plant Care

Black Mullein (Verbascum nigrum) belongs to the Scrophulariaceae family within the Verbascum genus. Black Mullein is native to dry open sites in temperate Europe. Black Mullein is also known as Dark Mullein.

Black Mullein displays a tall spires of flowers growth habit, reaching up to 4 ft tall with a spread of approximately 2 ft. Black Mullein produces large, showy spikes of yellow, pink, or purple flowers.

Leaf size: approximately 6 inches.

Water a young or newly planted Black Mullein 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.

Black Mullein thrives in full sun to part shade.

Verbascum nigrum tolerates temperatures of 50–80°F. Black Mullein prefers humidity levels of 40–70%.

Well-draining sandy loam with added compost for nutrients. Good drainage is essential for Black Mullein to prevent waterlogging, which leads to root rot and fungal issues.

Feed Black Mullein 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 part shade and well-draining sandy loam with added compost for nutrients. Avoid low spots where water collects after rain.

Black Mullein is suited to USDA Zone 5a – 9b.

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.

Black Mullein can spread to about 2 ft (0.6 m) and reach about 4 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 Black Mullein 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.

Black Mullein 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.

Black Mullein can be propagated through seeds, division of offsets. Similar propagation techniques also apply to bombyciferum mullein plant care, which shares the same genus.

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

Black Mullein is susceptible to aphids, slugs, snails. 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.

Black Mullein grows outdoors in USDA Zone 5a – 9b. It survives winters down to planting zone 5a. Black Mullein is native to dry open sites in temperate Europe.