Blue Rug juniper

Sun

Full sun; shade produces thinner growth and poorer foliage colour.

Water

Water regularly while establishing; drought-tolerant once rooted. Let the soil dry between waterings rather than keeping it constantly damp.

Soil

Well-drained sandy, gravelly or loamy soil, from acidic to alkaline. Avoid waterlogged ground and heavy clay unless drainage is improved.

Height

0.3-0.5 ft (0.1-0.15 m)

Spread

6-8 ft (1.8-2.4 m)

Foliage

Fine-textured, silver-blue to blue-green evergreen foliage on ground-hugging stems; often develops purple or bronze tones in cold weather.

Growth

Moderate; takes several years to form a broad carpet.

Care needed

Low

• Deer resistant
• Drought tolerant
• Cold hardy
• Heat tolerant
• Wildlife

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   0.1 ft (0.03 m)

2. After 1 year

   0.2 ft (0.07 m)

3. After 2 years

   0.3 ft (0.11 m)

4. After 3 years

   0.4 ft (0.13 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Mildly toxic: may upset a stomach

Native to

the US and Canada

Growth rate

Moderate

• Water deeply during dry spells through the first growing season, allowing the surface soil to dry between waterings.
• Leave enough space for its mature spread rather than relying on repeated trimming.
• Remove weeds before planting and hand-weed gaps until the branches cover the ground.
• Use a light gravel mulch on suitable sites; keep mulch away from the central crown.
• Feed only if growth is weak and soil is poor; avoid heavy nitrogen applications.
• Keep sprinklers off the foliage where possible, especially in humid weather.

Pruning. In spring, remove dead or damaged shoots and shorten stray branches back to a leafy side shoot. Do not cut into bare old wood, which usually will not regrow, and avoid shearing the whole plant.

Early spring

Check for winter damage and remove dead branches in dry weather.

Spring

Plant into well-drained soil, water thoroughly and keep surrounding weeds down.

Late spring

Inspect new shoot tips for browning; remove affected growth and check drainage.

Summer

Water young plants during dry spells; check stressed foliage for spider mites.

Late summer

Take semi-ripe cuttings if you want more plants of the same cultivar.

Autumn

Remove fallen leaves caught in the mat and check that winter rain can drain freely.

• Cover sunny slopes with a low evergreen carpet, allowing room for the stems to spread.
• Trail it over retaining walls to soften hard edges without obscuring the whole structure.
• Plant among boulders and gravel with dwarf conifers for contrasting shapes and textures.
• Use beneath upright ornamental grasses or beside sedums for a cool blue foreground.

Garden styles it suits: Low-maintenance, Dry gravel garden, Desert / xeriscape, Coastal, Winter interest and Alpine rock garden.

Plant it with: Dwarf mugo pine, Blue fescue, Russian sage, Catmint, Upright sedum and Creeping phlox.

Wildlife: The dense mat provides shelter for small animals and invertebrates. It offers little nectar or pollen value to pollinating insects.

• Root rot in wet soil: improve drainage or move the plant to a raised, freely draining site; replace plants with extensively rotted roots.
• Juniper tip blight: prune brown shoot tips back to healthy growth in dry weather, clean tools between cuts and avoid overhead watering.
• Spider mites in hot, dry conditions: look for fine stippling and webbing, rinse foliage thoroughly and use a labelled insecticidal soap if necessary.
• Bare patches from shade, trampling or severe cutting: remove the cause; old bare branches rarely fill out again, so badly damaged plants may need replacing.

Not known to be seriously toxic to people, cats, dogs or horses, although safety information specific to this cultivar is limited. Eating foliage or berry-like cones may cause stomach upset, and contact with the foliage or sap can irritate sensitive skin. Do not treat it as an edible juniper.

• Blue Chip juniper (Juniperus horizontalis 'Blue Chip')

  Also blue and spreading, but generally forms a taller, more uneven mound with more noticeably raised branch tips.

• Japanese garden juniper (Juniperus procumbens 'Nana')

  Forms a thicker, taller mound with conspicuously prickly, needle-like foliage rather than Blue Rug's flatter, finer-textured carpet.

• Blue Pacific shore juniper (Juniperus conferta 'Blue Pacific')

  Has longer, sharply pointed needles in groups of three and a looser, coarser appearance.

The species name horizontalis refers to its horizontal growth, while Blue Rug describes its low carpet of blue-toned foliage.

Propagation. Root semi-ripe cuttings in late summer in a freely draining medium. Low branches may also root where they touch the soil and can be separated once well rooted; seed will not reproduce the cultivar reliably.

Accepted botanical name

Juniperus horizontalis

In the US and Canada

Native in Alaska, Canada, the lower 48 states and St. Pierre and Miquelon.

Native range

Alaska, Alberta, British Columbia, Colorado, Illinois, Iowa, Labrador, Manitoba, Masachusettes, Michigan, Minnesota and Montana.

Measured

Soil pH 5.5 to 7.8. Average height 76 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.