Juniperus horizontalis, commonly called Creeping or Carpet Juniper, is a low-growing evergreen shrub. It is native to Alaska, Canada, and the northern U.S from New England to New York to the Great Lakes, Wyoming, and Montana. The cultivar is “Wiltonii”.

“Wiltonii” is synonymous with J.horizontalis “Blue Rug” and it also commonly called “Blue Rug juniper”.

The Features of Blue Rug Juniper

Native to North America, this Blue Rug noted for its excellent, prostrate, dense form. It will grow a little more slowly, typically grows to be 4-6 inches tall and spreading to 5-7 feet.

These evergreen shrubs make an excellent ground cover for mixed shrub beds, rock garden, mass plantings and erosion control.

Blue Rug juniper serves well as a year-round ground cover, its silvery blue foliage turning a bit purplish during the cold winter months.

In the cold regions, this Blue Rug adapts well to snow and frost but it can turn almost purple in seriously cold winters. That may be the main reason why some people found that the name to be deceptive since it never really looked blue when they had it.

The plants are dioecious, the male and female shrubs are separate. The female shrub produces blueberries from late spring to late winter. The flowers are not used for decorative purposes. The female “berries” were used by Native Americans to brew a tonic tea and may be eaten by grouse, wood rats, and deer.

Like other Junipers, these shrubs prefer full sun and well-drained soil with an acidic pH. They will creep in a leggier manner if suck in the shade.

Blue Rug Juniper can be grown in planting zones 3 to 9.

Buying plants from the garden center and trying to install them during mid to late summer (the hottest part of the year) is not a good idea as the summer’s heat will stress your young plants and make it hard to keep them watered well enough.

Planting time depends on the condition of the Blue Rug Juniper. Dormant stems and Bare root junipers. Planting bare root plants in the winter during the dormant season is the best while another form requires planting during the fall, winter or early spring (At this time, the temperatures remain below 60 degrees Fahrenheit).

Blue Rug Junipers are salt-tolerant plants, it is best planted near salted areas. So if your area is slightly salted, it will be a perfect condition for these plants.

If it is not your case, don’t worry. One of the great things you will see in this shrub is it can tolerate cold conditions, dry conditions, moist conditions, urban pollution, maritime salt-air environments, hard or gravelly soils, just anything except poor drainage or shade.

It is also highly recommended for uneven hillsides since it grows in a cascading manner downhill, conforming to the shape of the ground. If it is grown in a tall container or large hanging basket, it would likewise seek the downward path.


Adding compost to your prepared soil and mixing it into the top 9 to 12 inches.

Add nutrients to improve drainage and loosens the soil for planting. Remove dead, broken or mushy roots before planting.

Also, use pruning shears to cut through any circling roots to encourage outward growth.

To ensure the proper planting depth and reduce the chance of damaging the juniper’s root, make sure the hole twice as wide and 2 inches shallower than the root. Space multiple plants 5 to 7 feet apart to accommodate their mature spread.

Burying the plants no deeper than it was previously growing and spreading the Blue Rug juniper’s roots out over the hole’s bottom is important to a successful planting.

It’s important to remember that planting these plants in the correct method, in the right location, at the right time will help ensure their successful growth.

Caring for Blue Rug Juniper


This is a certain low maintenance plant and is best pruned once the threat of extreme cold has passed. That said, you may want to prune them back to about 5 inches from the edge of the bed in late winter.

The new growth will cover the pruned edges make them a new beautiful look. With skillful pruning, the shrubs will develop more branches resulting in denser groundcover as it spreads.

As a ground cover, space plants 5 ft. apart to form a dense enough mat to crowd out weeds and control weeds with mulch until the plants cover the area.


The Blue Rug juniper typically takes approximately 6 weeks to establish new roots in the soil. During this period, water it every 2-4 days.

After then, water once per week (If it doesn’t rain). You can stick your finger into the soil to check soil moisture for watering.


Generally, these shrubs rarely need additional fertilizing during the first year of growth. They are evergreen shrubs so can only use a small amount of fertilizer.

If you choose to fertilize your plant, it is recommended that a 1-inch-deep layer of mulch spread over the planting site will help conserve soil moisture and reduce weed growth.

Although this one is low maintenance, you might want to take care of a newly planted Blue Rug properly to increase its chance of survival and root establishment. Soggy soil will drown the roots and wither the plant, so it’s a great idea to provide it with supplemental watering when the top 1 to 2 inches of soil become dry.


There are no serious insect or disease problems with the Blue Rug Junipers. Occasional insect pests include bagworms, scale, webworm, aphids. Watch for spider mites as well. These plants are generally susceptible to blights and root rot may occur, particularly in unusually rainy/wet springs.

Uses in landscaping

This Juniper performs in a landscape very well. It can be used for many landscaping application such as ground cover, mass planting, border edging, general garden use, rock/alpine gardens.

This juniper spreads rapidly making it ideal for homeowners who are in a rush to install ground covers on a slope to control erosion. Depending on how close together you plant these shrubs, they can take a few years to fill in. Once filled in they make a perfect evergreen carpet that does a great job of keeping a bed weed tree.

What I personally like about this Blue Rug Juniper is the look it gives when spilling over a stone wall or along a rock garden.

Sometimes, I find it is used in a design where it was placed near a small whip of an old tree, since then the old tree will have grown and extended a huge leaf canopy over the juniper, robbing it of needed sunshine, that causing significant dieback.

Placed appropriately your Blue Rug juniper can be expansive, flowing evergreen carpet to really dress your garden.

Is Blue Rug juniper For you?

There are many factors to consider before answering this question. It’s important to ask yourself these questions.

Do you like plants that lay very close to the ground? If not, consider other than Blue Rug Juniper.

Can they get full sun from your planting site? If not, try other ones.

Do you have a small area? If yes, you should not plant them.

If you don’t have any concerns mentioned above, then this flowing evergreen carpet may be for you.

Substitute for Blue Rug Juniper

If you are thinking about the Substitute for Blue Rug Juniper, Blue Pacific juniper (Also called Pacific shore juniper) is a great alternative.

Some Facts about Blue Rug Juniper

  • Common Name(s): Blue Rug Juniper
  • Category: Groundcover
  • Height: 4-6 inches.
  • Width: 5-7 feet.
  • Planting zones: 3-9.
  • Foliage: Dense silver-blue foliage
  • Habit: Evergreen
  • Exposure: Full Sun
  • Texture: Fine
  • Form: Trailing; creeping
  • Growth Rate: Slow to moderate
  • Garden Uses A sprawling, versatile ground over. Rock garden. Retaining wall edges. Foundations. Good for rocky ground. Mass on slopes for erosion control. Hot and dry areas.