Annual Mercury Plant Care

Annual Mercury (Mercurialis annua) belongs to the Euphorbiaceae family within the Mercurialis genus. Annual Mercury is native to the Middle East and the Mediterranean region. Annual Mercury is also known as Wild Mercury, Cuckoo Spurge, Dog's Mercury.

Annual Mercury displays a low spreading groundcover growth habit, reaching up to 0.5 ft tall with a spread of approximately 1 ft. Annual Mercury produces small inconspicuous flowers.

Leaf size: approximately 2 inches.

Water a young or newly planted Annual Mercury 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.

Annual Mercury thrives in partial to full shade. The optimal light range is 50–200 lux. Avoid placing Annual Mercury in direct, harsh sunlight for extended periods, as this can scorch the foliage.

Mercurialis annua tolerates temperatures of 60–75°F. Annual Mercury prefers humidity levels of 40–60%.

Well-draining soil with high organic content. Good drainage is essential for Annual Mercury to prevent waterlogging, which leads to root rot and fungal issues.

Feed Annual Mercury every 8 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 to full shade and well-draining soil with high organic content. Avoid low spots where water collects after rain.

Annual Mercury is suited to USDA Zone 8a – 11b.

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.

Annual Mercury can spread to about 1 ft (0.3 m) and reach about 1 ft (0 m) tall. Space plants about 1 ft (0.3 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 Annual Mercury 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.

Annual Mercury is hardy down to USDA zone 8a, 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.

Annual Mercury can be propagated through seeds, stem cuttings. Similar propagation techniques also apply to dog's mercury plant care, which shares the same genus.

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

Annual Mercury is susceptible to aphids, 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.

Annual Mercury grows outdoors in USDA Zone 8a – 11b. It survives winters down to planting zone 8a. Annual Mercury is native to the Middle East and the Mediterranean region.