Shrub · Cupressaceae

Creeping Juniper

Juniperus horizontalis

Give it full sun and soil that drains, and this tough evergreen mat looks after itself.

Light

Full sun

Water

Every 10–⁠21 days

Hardiness

USDA 3–⁠9

Mature size

6–⁠18 in · 15–⁠46 cm

Pet-safe
Creeping Juniper

Overview

Creeping juniper is a low, mat-forming evergreen that spreads wide and stays close to the ground. It belongs to the cypress family and grows wild across cold reaches of North America, which is why it shrugs off winters down to -40°F (-40°C). A single plant can crawl 4 to 8 feet (122 to 244 cm) across while standing barely a foot tall.

Gardeners reach for it as a ground cover on slopes, in rock gardens, and along hot, dry banks where little else holds. It asks for almost nothing once it settles in, taking poor, sandy soil, salt, drought, and blazing sun in stride. The trailing branches root where they touch the ground, so the mat knits itself together over time.

The one thing it will not tolerate is wet feet. Plant it in ground that drains fast, keep water off the foliage, and give it room and air, and it stays healthy and trouble-free for decades. Crowd it or sit it in soggy soil and you trade that toughness for blight and root rot.

Care

The short version: full sun, fast-draining soil, and very little water once it's established. Skip the rich beds and frequent watering, give each plant room to spread, and let it dry out between drinks.

Light

Creeping juniper wants full sun, and plenty of it. Sun keeps the mat dense and the color true, while shade thins the foliage and invites the blight that goes after damp, crowded growth.

Water

Once established it is very drought tolerant and wants water only every 10 to 21 days, if that. Water deeply but rarely, let the soil dry out in between, and keep the spray off the foliage, since wet leaves bring on tip blight.

Soil

Give it fast-draining soil above all else, whether sandy, rocky, or poor. It takes a wide pH range from 5.5 to 8.0 and adapts to lean ground, but it will not survive in anything that stays wet.

Temperature

This is one tough evergreen, hardy from -40°F to 100°F (-40°C to 38°C). It handles brutal winters and baking summer heat without flinching, which is why it works on exposed banks where softer plants fail.

Humidity

Creeping juniper prefers low humidity and dry air around the foliage. Damp, still air is its enemy, so the answer is never to add moisture but to open the plant up so air moves freely through it.

Feeding

It barely needs feeding. A light balanced or slow-release fertilizer in spring helps only if growth has stalled, and a plant in average soil can go for years on nothing at all.

Pruning

Prune in dry weather to cut out dead, diseased, or blight-killed tips, going several inches below the damage into healthy wood and disinfecting your blades between cuts. Thin the mat now and then to open it up and keep air moving through the interior.

Repotting

It rarely needs repotting, and most plants live their whole lives in the ground. In a container, watch for roots circling or pushing out the drainage holes, water running straight through, or growth that simply stops.

Size & spacing

Plants stay low at 6 to 18 inches (15 to 46 cm) tall but spread 4 to 8 feet (122 to 244 cm) wide. Set them far enough apart to fill in over time without crowding, which keeps air moving and disease down.

When to plant

Creeping juniper goes in the ground in spring or early fall, when the soil is workable and the plant can settle its roots before extreme heat or hard frost. It produces small cones in late spring, and the blue berry-like cones take two full seasons to ripen. There's no harvest to chase, so timing is really about giving the roots a head start.

Northern hemisphere

Plant Mar–May
Bloom May–Jun
Plant Sep–Oct

Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.

  • Plant: Spring or early fall
  • Harvest: Inconspicuous cones in late spring; blue berry-like cones mature over two seasons

Hardiness

USDA hardiness zones: 3–9

Temperature: down to -40°C

Troubleshooting

Most juniper trouble traces back to two things: foliage that stays wet and soil that won't drain. Read the early signs on the tips, the inner branches, and the roots, and you can step in before a small patch spreads. Match what you see below, then act while it still helps.

Severe

Whole plant thinning out with roots gone brown

Wet feet bring on Phytophthora root rot, which rots the roots from white to reddish-brown and starves the top of the plant. There's no spray that cures it once the roots are gone. Let the soil dry, lift any plant that's badly hit, and replant in ground that drains freely.

Fix:

  • Allow soil to dry out; mildly affected plants may recover
  • Improve drainage by amending with organic matter or pine bark or planting in raised beds
  • Remove and discard severely affected plants
  • Replant with resistant species in well-drained sites
Setback

Branch tips browning and dying back from the ends

This is tip blight, caused by one of two fungi that move in when foliage stays wet. Phomopsis attacks fresh spring and summer growth, while Kabatina shows up on older, wounded tips in late winter. Prune the dead tips out in dry weather, cutting several inches into healthy wood, and disinfect the blades between every cut.

Fix:

  • Prune out blighted tips in dry weather, cutting several inches into healthy wood
  • Disinfect pruners between cuts with 10 percent bleach or 70 percent alcohol
  • Discard or destroy infected prunings
  • Apply a labeled fungicide preventively for Phomopsis as new growth emerges if pressure is high (no effective fungicide for Kabatina)
Setback

Dull, speckled foliage with fine webbing

Stippling and webbing point to spider mites, which build up fast on hot, dusty, stressed plants. They do their worst in the cool stretches of spring and fall. Blast them off with a strong jet of water, and reach for insecticidal soap or oil only if they keep coming back.

Fix:

  • Dislodge mites with a strong, regular spray of water
  • Apply insecticidal soap, horticultural oil, or a miticide if needed
  • Avoid broad-spectrum insecticides that kill mite predators
Setback

Spindle-shaped bags hanging from chewed branches

Those dangling bags are bagworms, caterpillars that feed from inside a silk case stitched together with bits of your juniper. Each bag holds eggs that overwinter and hatch into next year's crop. Pick the bags off through winter and early spring, and treat young larvae with Bt if they appear.

Fix:

  • Handpick and destroy bags in winter and early spring to remove overwintering eggs
  • Spray Bt or another labeled insecticide on young larvae in spring
Setback

Tiny white scales and sticky honeydew on the needles

Small white or gray bumps on the needle undersides are juniper scale, sap-feeders that leave the foliage off-color and tacky with honeydew. A dormant oil spray in late winter smothers them before they get going. Catch the crawlers in spring and an insecticide finishes the job.

Fix:

  • Apply horticultural oil as a dormant spray in late winter
  • Treat crawlers with a labeled insecticide during the spring growth flush
Cosmetic

Brown galls sprouting orange jelly horns in spring

These galls are cedar-apple rust, a fungus that needs an apple or crabapple nearby to complete its life cycle. The hard brown lumps swell into bright orange tendrils during wet spring weather. Prune the galls out, and keep junipers away from apples and crabapples in the first place.

Fix:

  • Prune out and destroy galls
  • Apply a labeled fungicide (mancozeb or propiconazole) if needed
  • Avoid planting near susceptible apples or crabapples
Cosmetic

Dead, brown branches buried inside the mat

When the canopy grows thick, the shaded interior loses light and air and the inner branches simply die off while the outside stays green. It's a siting and density problem, not a disease. Thin the plant to open it up, clear the dead wood in dry weather, and give it full sun with room to breathe.

Fix:

  • Thin and prune to open up the canopy and improve air movement
  • Remove dead interior branches in dry weather
  • Site in full sun with adequate spacing

Toxicity

Creeping juniper is a safe plant to keep around the home and garden. It isn't on the ASPCA toxic-plant lists, and the worst it usually causes is a mild stomach upset if a pet eats a lot of the aromatic berries or foliage. The bigger nuisance is the prickly foliage, which can scratch sensitive skin, so wear gloves when you prune.

Safe for

People · Cats · Dogs · Horses · Rabbits · Livestock · Birds

Cats Caution

Largely safe to be around. A cat that chews a lot of the aromatic foliage or berries may get a mildly upset stomach from the volatile oils, so it's worth steering them off the plant.

Dogs Caution

No real danger from a curious sniff. Eating a quantity of berries or foliage can bring on some drooling or a brief bout of vomiting and loose stool, which clears up on its own.

Horses Caution

Grazing the odd sprig does no harm, but the berries and resinous oils can irritate a horse's gut if it eats a large amount, so don't let them browse it heavily.

Rabbits Safe

Not a known hazard for rabbits, though the dense, prickly foliage holds little appeal and they tend to leave it alone.

Livestock Safe

Cattle, goats, and sheep can share a pasture with it without trouble, since the resinous, sharp foliage rarely tempts them to eat much.

Birds Safe

Perfectly fine for birds, which actually eat the blue cones and help spread the seed around.

People Safe

Safe to plant and handle, and some juniper berries are used as a culinary spice. The prickly foliage can scratch or irritate sensitive skin, so wear gloves when you prune.

Aromatic foliage and berry-like cones may cause mild stomach upset if eaten in quantity; the prickly foliage can also irritate skin in sensitive people.

Varieties

Most creeping junipers sold are named cultivars chosen for foliage color and how flat they grow. These are the ones you'll run into most.

Wiltonii (Blue Rug)

It forms a very flat, ground-hugging mat of silvery blue-green foliage.

Bar Harbor

A low, fast-spreading form with feathery blue-green foliage that picks up a mauve to purplish tinge over winter.

Plumosa (Andorra)

Its mounded, soft gray-green foliage turns a distinct plum-purple once the cold sets in.

Mother Lode

Bred from Wiltonii, it carries golden-yellow foliage on the same very low, flat mat.

Lime Glow

Bright lime to golden foliage forms a low vase-shaped mound that takes on bronze tones in winter.

How to propagate

You can multiply creeping juniper three ways, and the method you pick depends on how much patience you have and whether you need the new plants to match the parent.

Stem cuttingsModerate

Late fall to winter using semi-hardwood cuttings · Several weeks to a few months to root

Cuttings are the way to keep a named cultivar true to type. Take semi-hardwood cuttings from late fall into winter and treat them with rooting hormone, since juniper is slow to root and can take several weeks to a few months to take hold.

LayeringEasy

Spring through summer · One or more seasons

Layering plays to the plant's nature, because trailing branches already root on their own wherever they rest on the soil. Pin a low branch down from spring through summer and give it a season or more to anchor before you cut it free.

SeedDemanding

After cold stratification · Slow and variable, often a year or more

Seed is the hard road and best left to the patient. It needs cold stratification first, then germinates slowly and unevenly over a year or more, and it won't reproduce a cultivar true to type.

Myths

Myth

Creeping juniper is poisonous and will seriously harm any cat or dog that touches or nibbles it.

Reality

Juniperus doesn't appear on ASPCA toxic-plant lists, and the plant is generally treated as non-toxic. At worst, eating a lot of the aromatic foliage or berries causes a mild, self-limiting stomach upset rather than real harm.

Myth

Junipers thrive in moist, rich soil and do better with frequent watering.

Reality

Creeping juniper is built for drought and wants soil that drains freely. Wet, heavy, or overwatered ground is what brings on Phytophthora root rot, the one problem most likely to kill it.

Sources