Juniperus horizontalis 'Wiltonii'
blue rug juniper
Species native to northern North America — Newfoundland and Nova Scotia west to Alaska and south through the Rocky Mountains to Wyoming and Nebraska; rocky outcrops, sandy banks, and open exposed slopes
Overview
Juniperus horizontalis 'Wiltonii' is Blue Rug juniper (Wilton carpet juniper), a trailing flat evergreen conifer growing 4-6 inches (10-15 cm) tall and 6-8 feet (1.8-2.4 m) wide. Silvery blue-green to steel blue scale-like foliage densely pressed against trailing stems, turning plum-purple in winter. In Cupressaceae spp.. Among the flattest groundcover junipers available. The steel blue color and the plum-purple winter shift are the primary features. The species is native to northern North America (Newfoundland to Alaska). Trailing stems root where they contact soil. Berry-like cones contain thujone — toxic to pets. Susceptible to juniper-cedar rust and Phomopsis tip blight. Tolerates poor soil, drought, and exposed conditions. Does not tolerate wet feet or heavy shade. Non-toxic foliage (cones toxic to pets). Deer-resistant. Zones 3-9. Full sun. Growth rate is slow.
Native Range
Species native to northern North America — Newfoundland and Nova Scotia west to Alaska, south through the Rocky Mountains to Wyoming and Nebraska. Found on rocky outcrops, sandy banks, and open exposed slopes.Suggested Uses
Grown as a flat evergreen ground cover on slopes, over walls, and in dry exposed sites, spaced 6-8 feet (1.8-2.4 m). One of the flattest junipers. Steel blue summer, plum-purple winter. North American native. Cones toxic to pets. Zones 3-9.How to Identify
Appearance
Size & Dimensions
Height4" - 6"
Width/Spread6' - 8'
Reaches mature size in approximately 7 years
Bloom Information
Not ornamentally significant. Dioecious. Berry-like cones rarely produced on this cultivar. Wind-pollinated.
Detailed Descriptions
Foliage Description
Silvery blue-green to steel blue, scale-like, overlapping, densely pressed against the trailing stems; turns plum-purple in winter — a distinctive seasonal color shift; one of the flattest and most intensely blue groundcover junipers; evergreen year-roundGrowing Conditions
Sun Requirements
Requires 6-12 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
Full sun (6-12 hours). Well-drained soil pH 5.5-7.5. Very low water needs. Does not tolerate wet feet or heavy shade. Susceptible to juniper-cedar rust and Phomopsis. Cones toxic to pets. Minimal pruning. Deer-resistant. Zones 3-9.Pruning
Prune in early spring (March-April) if needed to control spread or remove dead tips. The natural flat trailing form requires minimal pruning.Pruning Schedule
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early spring