Shrub · Cupressaceae

Creeping Juniper

Juniperus horizontalis

Hand it full sun and quick-draining ground, and this hardy evergreen carpet tends 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 lays down a low, mat-forming sheet of evergreen needles that travels wide and barely lifts off the ground. A member of the cypress family, it grows wild through the cold stretches of North America, so it brushes off winters as deep as -40°F (-40°C). One plant can trail 4 to 8 feet (122 to 244 cm) sideways while rising scarcely a foot from the soil.

Gardeners lean on it to cover slopes, rock gardens, and baking dry banks where almost nothing else clings on. After it roots in, it asks for next to nothing, taking thin sandy soil, salt, drought, and full glare in stride. The trailing branches strike roots wherever they press down, so the carpet stitches itself tighter season after season.

Its one hard limit is standing water at the roots. Set it in soil that drains quickly, keep moisture off the needles, and leave it room and moving air, and it stays healthy and trouble-free for decades. Pack it in tight or leave it in sodden ground and that toughness gives way to blight and root rot.

Up close the needles are scale-like and aromatic, packed in dense sprays of silvery blue-green that throw mauve and purplish tints in some cultivars come winter. The branches carry small, round blue berry-like cones, dusty and pale, that take their time ripening over two seasons.

Care

The short version: full sun, quick-draining soil, and barely any water once it is settled in. Pass on the rich beds and the steady watering, leave each plant space to trail out, and let it parch between drinks.

Light

Creeping juniper craves full sun, and a generous helping of it. Strong light packs the mat dense and holds the needle color true, while shade thins the foliage out and opens the door to the blight that hunts damp, crowded growth.

Water

Once it is rooted in it is very drought tolerant and wants a drink only every 10 to 21 days, if even that. Soak it deeply but seldom, let the soil parch between, and keep the spray off the needles, since wet foliage invites tip blight.

Soil

What it needs above all is fast-draining soil, sandy, rocky, or lean alike. It accepts a broad pH stretch from 5.5 to 8.0 and copes with poor ground, but it cannot pull through in anything that stays soggy.

Temperature

This is a flinty evergreen, hardy across -40°F to 100°F (-40°C to 38°C). It rides out savage winters and scorching summer heat without complaint, which is why it earns its place on bare banks where tender plants give out.

Humidity

Creeping juniper favors low humidity and dry air moving past the needles. Still, damp air is its undoing, so the fix is never to add moisture but to open the plant so air slips freely between the sprays.

Feeding

Feeding is almost beside the point. A light balanced or slow-release feed in spring helps only when growth has stalled, and a plant in ordinary soil can run for years on nothing whatsoever.

Pruning

Prune in dry weather to clear out dead, diseased, or blight-killed tips, reaching several inches past the damage into firm green wood and wiping your blades clean between cuts. Thin the mat from time to time to loosen it and keep air slipping through the core.

Repotting

Repotting is rarely called for, and most plants spend their whole lives rooted in the ground. In a pot, keep an eye out for roots circling or shouldering out the drainage holes, water draining straight through, or growth that flat-out halts.

Size & spacing

Plants hold low at 6 to 18 inches (15 to 46 cm) tall yet trail 4 to 8 feet (122 to 244 cm) wide. Place them far enough apart to knit together in time without jamming, which keeps air on the move and disease at bay.

When to plant

Set creeping juniper into the ground in spring or early fall, while the soil works easily and the roots can dig in ahead of fierce heat or a hard freeze. Small cones appear in late spring, and the round blue berry-like cones need two full seasons to color up. There is nothing to harvest, so the timing is all about handing the roots an early 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

Almost every juniper problem comes down to two culprits: needles that stay wet and soil that holds water. Read the early clues on the shoot tips, the buried inner stems, and the roots, and you can move in before one bad patch races outward. Pair what you spot below with its match, then act while acting still counts.

Severe

Foliage thinning everywhere while the roots turn brown

Soggy ground invites Phytophthora root rot, which darkens the roots from creamy white to reddish-brown and cuts off the supply line to the foliage above. Once the roots are lost, no spray brings them back. Let the soil dry, dig out anything hit hard, and set it again where water drains away fast.

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 fading to brown and shriveling back from the ends

What you are seeing is tip blight, the work of one of two fungi that take hold while the foliage sits wet. Phomopsis goes after soft new spring and summer shoots, and Kabatina settles into older, nicked tips by late winter. Cut the dead ends away on a dry day, several inches down into firm green wood, and wipe the blades clean between every snip.

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

Flat, speckled foliage strung with fine webbing

Yellow stippling and that thin webbing across the needles mean spider mites, which multiply fast on plants left hot, dusty, and strained. They peak through the cooler runs of spring and fall. Knock them loose with a hard burst of water, and only turn to insecticidal soap or oil if they push 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

Tapered silk pouches dangling over chewed branches

Those hanging pouches are bagworms, caterpillars that eat from inside a silk case studded with snips of your own juniper. Each case is packed with eggs that ride out winter and hatch the following year. Pull the bags off through winter and into early spring, then hit young larvae with Bt if they show.

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

Pale scaly specks and a sticky film coating the needles

Little white or gray bumps clustered on the undersides of the needles are juniper scale, sap-suckers that leave the foliage dull and slick with honeydew. A dormant oil spray late in winter smothers them before they wake. Catch the spring crawlers and an insecticide closes things out.

Fix:

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

Hard brown lumps pushing out orange jelly horns in spring

Those swollen lumps are cedar-apple rust, a fungus that has to find an apple or crabapple close by to finish its cycle. The dry brown galls plump up into glistening orange tendrils through damp spring spells. Snip the galls off the branches, and keep junipers clear of apples and crabapples from the start.

Fix:

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

Brown, lifeless stems hidden deep in the mat

As the canopy thickens, the shadowed core loses both light and airflow, so the inner stems brown out and die while the outer surface stays green. This is about siting and crowding, not infection. Thin the plant to let it breathe, clear the dead wood on a dry day, and plant it in full sun with elbow room.

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 have around the house and yard. It does not appear on the ASPCA toxic-plant lists, and the most it usually triggers is a mild stomach upset when a pet eats a lot of the aromatic cones or needles. The real nuisance is the prickly foliage, which can scratch tender skin, so glove up before you prune.

Safe for

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

Cats Caution

Mostly harmless to live alongside. A cat that crunches through a lot of the resinous needles or cones may feel a mildly queasy stomach from the volatile oils, so it is worth nudging them away from the plant.

Dogs Caution

A curious sniff poses no threat. Down a quantity of the cones or foliage, though, and a dog may drool, throw up briefly, or pass loose stool, all of which settles by itself.

Horses Caution

Nibbling a stray sprig causes no harm, but a bellyful of the cones and resinous oils can upset a horse's gut, so keep them from browsing it heavily.

Rabbits Safe

Poses no known threat to rabbits, and the thick, prickly needles hold so little appeal that they usually walk on past.

Livestock Safe

Cattle, goats, and sheep can graze a pasture with it close by and come to no harm, since the sharp, resinous foliage seldom tempts a real mouthful.

Birds Safe

Entirely fine for birds, which feed on the blue cones and carry the seed off to new ground.

People Safe

Safe to plant and to handle, and certain juniper berries season food as a spice. Those stiff, prickly needles can nick or sting tender skin, so pull on gloves before 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

Nearly every creeping juniper for sale is a named cultivar picked for needle color and how flat it grows. These are the ones you are most likely to meet.

Wiltonii (Blue Rug)

Its silvery blue-green needles press down into an exceptionally flat carpet that hugs the ground.

Bar Harbor

Quick to spread and low to the ground, its feathery blue-green foliage warms to a mauve and purplish cast through winter.

Plumosa (Andorra)

Soft gray-green foliage piles into low mounds that shift to a clear plum-purple when the cold arrives.

Mother Lode

A Wiltonii seedling that swaps the blue tone for golden-yellow needles on the same flat, ground-pressed mat.

Lime Glow

Lime to golden needles build a low vase-shaped mound that deepens toward bronze through the cold months.

How to propagate

Creeping juniper can be increased three ways, and which one suits you turns on how patient you are and whether the new plants have to look just like the parent.

Stem cuttingsModerate

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

Cuttings hold a named cultivar true to its parent. Pull semi-hardwood cuttings from late fall into winter, dust them with rooting hormone, and wait, because juniper is reluctant to root and can need several weeks to a few months to take hold.

LayeringEasy

Spring through summer · One or more seasons

Layering leans on what the plant already does, since the trailing branches strike roots on their own anywhere they meet bare soil. Peg a low stem to the ground from spring through summer and allow it a season or more to anchor before cutting it loose.

SeedDemanding

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

Seed is the slow, stubborn route, fit for the patient only. It demands cold stratification first, then sprouts thinly and unevenly across a year or more, and it will not copy 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 is missing from ASPCA toxic-plant lists, and gardeners treat the plant as non-toxic. At worst, a big mouthful of the resinous needles or cones brings a mild, self-limiting stomach upset instead of any lasting harm.

Myth

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

Reality

Creeping juniper is made for dry ground and needs soil that sheds water quickly. Wet, heavy, or overwatered ground is what brings on Phytophthora root rot, the single problem most able to kill it.

Sources