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Empetrum spp.
Circumpolar Northern Hemisphere and southern South America
Overview
Empetrum spp. is a small genus of about three low, evergreen, heath-like shrubs in the family Ericaceae, called crowberries. They grow as dense, spreading mats 4 to 12 in (10 to 30 cm) tall, with wiry stems clothed in small, needle-like leaves that have inrolled margins, giving the shoots a heather-like look. The tiny flowers are pink to purplish and easily overlooked, opening in spring, with male and female flowers usually on separate plants. Female plants bear rounded berries that ripen black in E. nigrum or red in E. rubrum, each about 0.2 in (5 mm) across and edible, though bland. Crowberries form a major ground cover across arctic tundra, northern moorland, and high mountains of the Northern Hemisphere, with E. rubrum extending to the southern tip of South America. They are extremely cold-hardy but need cool conditions, and tolerate neither heat, drought, nor lime, which makes them hard to grow in warm or low-elevation gardens.
Native Range
Native to cold-temperate, subarctic, arctic, and alpine regions of the Northern Hemisphere, including northern North America, Greenland, Iceland, northern Europe, and northern Asia, with E. rubrum in southern South America and subantarctic islands.Suggested Uses
Grown as an evergreen ground cover in cool-climate rock gardens, peat beds, and heather plantings on acid soil. The berries are gathered from wild and cultivated plants for preserves and traditional foods in northern regions. It suits exposed, cold sites where few other shrubs persist.How to Identify
Appearance
Size & Dimensions
Height4" - 1'
Width/Spread1' - 3'
Bloom Information
The inconspicuous pink to purple flowers open in spring, from about April to June depending on latitude and altitude. Male and female flowers are usually borne on separate plants. Berries ripen in late summer and may persist into winter.
Detailed Descriptions
Flower Description
Pink to purpleFoliage Description
Dark greenGrowing Conditions
Sun Requirements
Requires 4-8 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
Crowberries grow in cool climates on permanently moist but free-draining acid soils rich in peat, at a low pH from about 4.0 to 5.5. They need full sun to light shade and consistently cool, damp conditions, and fail where summers are hot or soils are alkaline. Plants are very hardy, withstanding the cold of USDA zone 2. Both male and female plants are needed for berries to set. A mulch of peat or leaf mould keeps the shallow roots cool and moist. Plants establish slowly and recover poorly from transplanting once settled.Pruning
Pruning is rarely needed. Straggly or winter-damaged shoots can be trimmed lightly in spring to keep the mat dense. Plants are otherwise left to spread on their own.Container Growing
✓ Suitable for container growing
Minimum container size: 2 gallons