Marrubium vulgare
white horehound
Europe, North Africa, and central Asia
Overview
Marrubium vulgare is an aromatic perennial herb in the mint family, growing 12-24 inches (30-60 cm) tall and 12-18 inches (30-45 cm) wide, with square stems covered in white woolly hairs. The wrinkled, rounded leaves are 1-2 inches (2.5-5 cm) long, gray-green, and densely felted, with scalloped margins. From June to September, dense whorls of small white two-lipped flowers cluster in the leaf axils along the upper stems. The calyx teeth become hooked in fruit and catch on fur and clothing, dispersing the seed. The whole plant is bitter and has a musky scent when crushed. Native to Europe, North Africa, and central Asia, M. vulgare has naturalized across North and South America, Australia, and other regions, where it colonizes overgrazed pasture, roadsides, and dry waste ground. It is listed as a noxious weed in several areas because it spreads readily on disturbed, dry land and is left alone by grazing stock. The plant tolerates poor, dry soil and drought, and dies back in cold winters before regrowing from the base. It is hardy to USDA zone 4.
Native Range
Native to Europe, North Africa, and central and western Asia. Naturalized worldwide in temperate and semi-arid regions, including much of North America, where it grows on dry, disturbed ground.Suggested Uses
Grown in herb gardens, dry borders, and gravel and pollinator plantings, and harvested as a traditional bittering and cough herb. Spaced 12-18 inches (30-45 cm) apart, it forms a low gray-green mound in hot, dry sites.How to Identify
Appearance
Size & Dimensions
Height1' - 2'
Width/Spread1' - 1'6"
Reaches mature size in approximately 2 years
Bloom Information
Flowers open from June to September in tight whorls along the upper stems. Bloom continues over a long summer season. As the flowers fade, the spiny, hooked calyces persist and hold the seed.
Detailed Descriptions
Foliage Description
Gray-greenGrowing Conditions
Sun Requirements
Requires 6-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Marrubium vulgare grows in full sun in dry, poor, well-drained soil across a pH of 6.0 to 8.0, and tolerates sandy, rocky, and alkaline ground. It is drought-tolerant and needs little or no water once established. The plant is hardy to USDA zone 4 and regrows from the base after winter dieback. Because it self-seeds heavily and is regulated as a weed in some regions, removing flower heads before seed set limits its spread. It has few pests. Rich, moist soil shortens its life and encourages rot.Pruning
Cut the plant back after flowering to reduce self-seeding and keep the clump compact. Removing dead stems in late winter clears the way for spring growth. Hard shearing in midsummer can prompt a flush of fresh gray foliage.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
wintersummer
Container Growing
✓ Suitable for container growing
Minimum container size: 2 gallons