If you’re looking for a quickly-spreading ornamental ground cover for your garden that is showier than traditional grass, you might love the needle-like, bushy foliage of creeping juniper.
I. Appearance and Characteristics
Juniperus horizontalis, the creeping juniper or creeping cedar, is a low-growing shrubby juniper native to northern North America, throughout most of Canada from Yukon east to Newfoundland, and in some of the northern United States. There are over 100 cultivars of creeping juniper.
Living up to both its scientific and common names, the species reaches only 10–30 centimeters (3+7⁄8–11+3⁄4 in) tall but often spreading several meters wide. The shoots are slender, 0.7–1.2 millimeters (1⁄32–1⁄16 in) diameter. The leaves are arranged in opposite decussate pairs, or occasionally in whorls of three; the adult leaf blades are scale-like, 1–2 mm long (to 8 mm on lead shoots) and 1–1.5 mm (1⁄32–1⁄16 in) broad, and derive from an adnate petiole. The juvenile leaves (on young seedlings only) are needle-like, 5–10 mm (3⁄16–3⁄8 in) long.
The cones are berry-like, globose to bilobed, 5–7 mm (3⁄16–9⁄32 in) in diameter, dark blue with a pale blue-white waxy bloom, and contain two seeds (rarely one or three); they usually have a curved stem and are mature in about 18 months. The male cones are 2–4 mm (3⁄32–5⁄32 in) long, and shed their pollen in early spring. It is dioecious, producing cones of only one sex on each plant.
It is closely related to Juniperus virginiana, and often hybridizes with it where their ranges meet in southern Canada. Hybrids with Juniperus scopulorum also occur.
| Common name | Creeping Juniper |
| Botanical name | Juniperus horizontalis |
| Family | Cupressaceae |
| Species | horizontalis |
| Origin | Northern North America into Canada |
| Life cycle | Woody |
| Plant type | Shrub |
| Hardiness zone | 3, 4, 5, 6, 7, 8, 9 |
| Sunlight | Full Sun |
| Maintenance | Low |
| Soil condition | Sand |
| Soil ph | Acid |
| Drainage | Well-Drained |
| Growth rate | Medium |
| Spacing | 6 – ft. – 12 ft. |
| Flowering period | Spring |
| Height | 6 in. – 1 ft. 6 in. |
| Width | 6 in. – 1 ft. 6 in. |
| Leaf color | Blue |
| Fruit color | Blue |
| Stem color | Brown, Copper |
| Leaf benefit | Long-lasting |
| Garden style | Drought Tolerant Garden |
| Uses | Coastal |
II. How to Grow and Care
Sunlight
Creeping juniper needs full sun—at least six hours of direct sunlight each day—to thrive. If planted in a shaded location, it will not spread or have vibrant color.
Temperature and Humidity
Creeping juniper is popular in part because of its ability to thrive in a mix of temperatures. Arid, hot summers aren’t a problem, and it can cope with cold, snowy conditions too; this plant is hardy down to USDA gardening zone 3, where winter temperatures can be as cold as 40 degrees below zero.
Watering
Creeping juniper is not happy in soggy, soaked soil, so overwatering is the biggest thing to avoid with your plants. Whenever the soil directly surrounding the root ball feels dry, give it a deep soak then let it dry out again. Creeping juniper will need extra watering when it’s newly planted.
Soil
Like many groundcovers and drought-tolerant plants, creeping juniper can grow in a variety of soils. However, it prefers sandy soil with medium moisture and excellent drainage. It can’t tolerate wet soil, so either make sure your soil has adequate drainage or add some extra perlite or sand to increase porosity. If you plant creeping juniper in sandy soil, you’re set!
Fertilizing
Creeping juniper doesn’t require fertilizer, but a light application of slow-release fertilizer or compost won’t do any harm. Supply with food in the late winter or early spring, before any new growth appears. Be sure to stop feeding before the first frost to protect your plant from growing new, vulnerable branches.
Planting Instructions
You can propagate creeping juniper from cuttings, but this slow-growing plant will take years to establish if you choose to plant it that way. The quickest way to plant creeping juniper is by transplanting a mature plant that you have purchased from a garden center. Here is an overview of how to plant creeping juniper by transplanting it.
- Choose your location and amend your soil: Your creeping juniper will need full sun and well-draining soil to thrive, although they can tolerate sandy soil or poor soils. Plant your creeping juniper in a location with lots of space because it will spread out. Try growing junipers near retaining walls or in rock gardens as ground cover.
- Prepare the soil and plant: Dig a small hole in the soil that is roughly twice the size of your juniper plant’s root ball. Carefully remove your creeping juniper from its pot and gently knead the root ball to prepare it for planting.
- Plant your creeping juniper: Plant your creeping juniper in the ground so that its roots are covered, then backfill the hole with soil and some mulch and gently pat down the soil.
- Water: Immediately water your creeping juniper after you plant it in the soil. Following this initial watering, your creeping juniper should need very little watering or none at all.
Pruning
Creeping juniper does not require regular pruning. If it grows larger than you’d like, you can trim it back to fit your space, but it’s best to choose varieties that are appropriately sized for your growing area whenever possible.
Propagation
You can propagate creeping juniper at any time except in extreme winters. Spring or early fall is the ideal time to move your plant or plant a new batch. All you have to do is dig the entire plant and its roots and replant it elsewhere.
Propagating from existing juniper plants through cuttings can be an exhausting process and will take years before you can see significant growth, so it’s usually better to buy more at the local nursery or garden center.
Pests and Diseases
All junipers are known for being downright tough. The annoying bugs and pathogens that make a meal out of so many plants seem to ignore junipers. And even if they are attacked by something, they tend to survive better.
- Common Pests
You have to love a plant that is pretty much untroubled by pests. Still, no plant is totally immune to pesky visitors. While it’s unlikely that you’ll ever have to worry about infestations, you should be aware of the few to watch for.
Spider Mites
Spruce spider mites (Oligonychus ununguis) love to gnaw on junipers and spruces.
These teeny-tiny spider relatives use their even tinier mouthparts to penetrate the bark and suck the sap from inside. They’re so small that they’re difficult to see with the naked eye, so watch for the symptoms instead.
Look for yellow spots on the foliage and browning, dying leaves. You might also see super fine webbing all over the plant. They thrive in the cool weather of spring and fall. Left unchecked, they can destroy a juniper in just a few years.
Their presence is usually a sign that something is out of whack in your garden, whether that’s an overuse of pesticides or a lack of biodiversity to draw in natural predators like lacewings and ladybugs.
Control is simple. Just blast the stems and leaves with a strong spray of water once every few days and trim off any dead bits. Keep at it for a few weeks, especially in the spring and fall.
Don’t use pesticides to control these pests. You might stop them in the short term, but chances are they’ll return with a vengeance.
Scale
Juniper scale (Carulaspis juniperi) is extremely similar to mites in that an infestation signals a larger problem in your garden. The symptoms also look the same, though they don’t produce fine webbing.
If you look closely at the stems, you can actually see these bugs. They look like little lumps and bumps all over the stems. If you scrape them, they’ll come off.
Don’t sit on this problem if your juniper is loaded with scale. After a few years of feeding, your juniper may be beyond saving. Treatment takes a few seasons, too.
Spray the plant with horticultural oil thoroughly in late fall, again in mid-winter, and once more in early spring. This smothers the adults and developing juveniles.
Horticultural oil is a nice product to keep around because it can serve many purposes in the garden.
Pick up a quart of ready-to-use or ready-to-spray horticultural from Monterey, or pint-, quart-, or gallon-size concentrate, at Arbico Organics.
- Common Disease
All junipers are susceptible to cedar apple rust, but J. horizontalis much less so. Instead, be on the lookout for blight.
Blight
There are several types of blight that may impact junipers, but Cercospora blight is the most common.
Caused by the fungus Cercospora sequoiae var. juniperi, you’ll know your plants have it when the inside, lower leaves turn brown.
These are the older leaves and they’re typically the first to be impacted by this disease. Over time, it spreads to the upper, outer leaves.
When you see these symptoms, prune the infected branches off. That should be enough to take care of the problem.
But if not, copper fungicide can finish the job. I try to always keep copper fungicide on hand because it can tackle a number of different diseases and it isn’t as terrible for the environment as some other harsh chemicals can be.
III. Types of Creeping Juniper
Reaching up to 2 feet, low-growing creeping junipers can spread easily to 6 to 8 feet. There are three main varieties:
- Juniperus horizontalis “Wilton,” can grow as high as six inches and is a spreading shrub that grows to 8 feet. It has silver-blue foliage and is more common in 4 to 10 zones.
- Juniperus procumbens “Nana” is a compact plant that can grow up to 1 to 2 feet in height and width. It has soft blue-green foliage and grows well in zones 7-11.
- Juniperus conferta or Shore Juniper is ideal for sandy and poor soils. If you live in zones 5 to 10, you can grow Shore Juniper. It bears golden-green foliage and can spread out to 8′ wide and 12-15″ tall.
IV. How to Get Creeping Juniper to Bloom
Like most members of the juniper family, creeping juniper is a dioecious plant, which means that there are separate male and female plants, and one of each is required to produce viable seeds. While male and female creeping junipers look the same in terms of foliage and growth habits, they show their difference in their flowers. The male flower is a cone-like structure with yellow-brown scales. These are generally 1/10 to 1/8 inches long. Female flowers are around half that size, have a bud-like shape, and are white to pink. Both male and female creeping junipers produce their flowers in the spring.
If wind carries pollen from a male plant’s flowers to a nearby female plant’s flowers, fertilization can occur. The female flowers will then eventually produce blue-gray, small berries, each containing two or three seeds. It can take up to two years for the berries to mature. Not all cultivars reliably produce berries, however.
V. Uses and Benefits
As the name suggests, creeping juniper is an excellent choice for ground cover in a garden. It tolerates hot and dry environments well, so rock gardens and gardens with poor soil quality are good settings for it. Because it thrives even in challenging soils, it can be used for areas where soil erosion is a concern, and near structures like walls. Some gardeners like to keep it alongside other plants with blue foliage.
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