Creeping Juniper Ground Cover: Types, Care, and Propagation
Overview of Junipers
Juniper is a coniferous plant of the Cypress family that comes in many varieties and grows across many climate zones. Most are found in the Northern Hemisphere. Junipers can range from tall evergreen trees, to shrubs, to groundcover varieties. They can be recognized by their needle shaped leaves, which turn scaly as the plant matures. Juniper trees have characteristic blue-colored berries at the ends of their branches. All juniper types produce cones.
Some Juniper is monecious—it has both male and female plant parts, and can reproduce even though only one tree or shrub is present. Pollen from the male plant parts can get into the air and reach the female cones. The berries that then around found on the plant are what encapsulate the seed. Creeping juniper is dioecious. This means that some plants are male and some are female, and one of each must be present for reproduction to occur. Both produce cones. Females can be distinguished from males by the berries they produce after they mature.
Juniper has several medicinal properties, and various plant parts are used for medical purposes. Juniper is believed to act as a diuretic or antiseptic.
Creeping Juniper Characteristics
Creeping juniper, sometimes also called creeping cedar, is a low lying evergreen groundcover. Within the taxonomy of the plant kingdom they are referred to as juniperus horizontalis. Although there are several varieties, they all grow usually no more than 2 feet tall, and will spread and extend roots as they do so. Most will spread about 8 feet. Some extend to 10 feet or more. If they are in a container or on a ledge, they will continue growing and “cascade” over the side. Creeping junipers usually expand their width by 1 to 2 feet each year.
Stems and Branches
Creeping juniper will start with a main, thicker trunk that is brown or gray. Smaller branches will grow off in different directions from that one, staying close to the ground. Those branches, once established, will have the same color as the trunk. New growth stems will be yellowish green. As the plant “creeps,” its new shoots will extend shallow roots that anchor it to the ground.
The leaves of creeping juniper are fine, green to blue feather-like needles. Many cultivars exist, and some are truer green while others are closer to a blue-gray hue. The leaves turn scaly as the plant matures. In the fall and winter, they turn to a purplish red color, but return to green when spring comes.
Female plants will produce bluish purple berries, which are actually the “cones” of this conifer. These berries are edible. Juniper berries are used to flavor gin. Some people also use them to make sauces.
Types of Creeping Juniper
There are over 50 species of the genus juniperus total, and juniper horizantalis is just one of those species. Within the species, over 100 cultivars are used and sold in nurseries. Below are some of the most popular varieties if creeping juniper. Unless otherwise noted, these will grow in USDA hardiness zones 3-9.
Blue Rug (Wiltonlii Juniper)
This is likely the most popular cultivar. It has a silver blue color and grows 6 inches or less off the ground. It spreads very quickly, and will likely expand several feet in the first season alone after being transplanted from a nursery. It pairs nicely with other evergreens, below trees, or along hardscapes.
This cultivar grows taller than most creeping junipers. It commonly grows to 1 foot tall or greater. It also has a blue green color, a shade between that of Blue Rug and Prince of Wales. It is native to Maine.
Blue Acres is blue in color, and spreads farther than any other variety. It commonly reaches up to 20 feet in width. This makes it a good choice for a quick groundcover. It is hardy in zones 4-9.
The blue leaves of this variety are denser than on other types. After a few years of growth, it may reach up to 3 feet tall and 4 feet wide. It is native to central Asia, and grows well in rocky, alpine environments. It will grow in zones 4-8, a narrower range than most junipers.
Emerald spreader is also low-lying, only reaching about ¾ foot tall. It is a green to slightly blue-green color. This variety is mostly found in Alaska and Canada, but also will grow in some parts of the northern United States. It will spread between 4 and 10 feet.
This type of creeping juniper is forest green colored, and will quickly cover expanses up to 8 feet wide.
Prince of Wales
The forest-green foliage of this variety is about average in height when compared to other creeping junipers. It reaches about 6 inches tall.
Lime glow is a yellow-green, much lighter shade than other creeping junipers. The leaves turn an orange-gold color in cold weather. It does not grow as quickly as other cultivars, and will usually only reach about 3 ½ feet wide.
Also referred to as dwarf creeping juniper, this type grows much closer to the ground. It almost resembles moss, and is forest green in color. Pancake creeping juniper will only reach up to 3 inches above ground, but will spread several feet horizontally.
Planting and Ongoing Care
Plant creeping juniper in a spot where it has room to spread. Also, make sure it will receive plenty of sun. Many people use it to fill in spaces in garden beds, along slopes in place of grass, or to drape over retaining walls. It will grow around rocks or other barriers, and is great for rock gardens or xeriscape (low water) landscaping.
This groundcover is not particularly picky about soil, but will do best in soil that drains well. They don’t usually need extra organic matter or other soil amendments in order to thrive.
USDA Hardiness Zones
Creeping junipers do better in more northern zones, but will grow up to zone 9. Many are native to Alaska and central Canada.
These plants require full sun to thrive. If grown in the shade they won’t look as vibrant, and won’t reach their full spreading potential.
Juniper is classified as drought tolerant. It can survive in drier conditions. When first transplanting, take care to make sure it doesn’t dry out for the first few weeks. After that, it should only need watering if you are receiving less than 1 inch of rainfall per week.
Don’t fertilize your juniper plant until it has been growing in its new permanent location for at least a full year. After that, you can use the same fertilizer you would use on other shrubs or trees. Do this in the fall.
Juniper, along with other evergreens, can be planted almost any time of year that the ground is not frozen. Spring or early fall are best. If you are digging up a plant to move somewhere else, you will need to dig up the entire plant, as well as any runners that have rooted. Unless the plant is fairly young, this may be a pretty big task. In most cases, you are better off purchasing a new plant from a nursery rather than trying to move an old one. If you have the patience, you can propagate your existing juniper plant from cuttings. This method will require waiting several years for a substantial plant to grow, however.
Plants that appear to be yellowing may have a fungal infection. If you spot this problem, carefully trim away damaged parts of the plant right away. Sterilize whatever tool you use before using them elsewhere in the garden to avoid spreading disease.
Pests that may afflict creeping juniper are bagworms, spider mites, aphids, or leaf aphids. To control bagworms, remove any webbing or bags you may see growing on the plant. For other pests, use a pesticide that indicates it is safe for use on shrubs, and that specifically targets the problem insect.
Landscaping and Pairing with Other Plants
This low growing shrub is suitable for many landscaping and garden layouts. It makes a good groundcover if you have a hill that is difficult to mow: just replace grass with creeping juniper. It will eventually fill in the area, and you won’t have to cut the grass there. It also will block light from reaching weeds.
Many people like to plant creeping juniper around mailboxes or other places that are hard to water. They are pretty resistant to drought. They also go well in hardscapes or in rock gardens, since they don’t have very particular soil requirements.
Creeping juniper looks nice when paired with other evergreens of varying height and colors. They also are lovely next to or in front of rose bushes. To fill in an empty space, you can combine it with other groundcovers like creeping phlox (also evergreen in some zones), creeping sedum, or creeping thyme.
Creeping juniper can be grown either from cuttings or from seed. Growing via cuttings is a much faster method, and will produce a plant that is identical to the original. This is the preferred method of propagation.
To grow using cuttings, take a soft wood (newer growth) cutting from an existing plant anytime between July and November. The cutting should be between 8 and 10 inches long. Prepare a planter with seed starting mix (one that does not have soil, but rather peat moss, vermiculite, or a combination), and create a hole where the cutting will go with a knife or a pencil. Take off the leaves from the bottom third of the cutting. Cut a few small slits in that bottom third. Put the cutting in the hole in the seed starting mix. Carefully push the growing medium around the base of the cutting so that it is set firmly. Water or mist carefully until the mixture is moist. Cover the container with a plastic bag (a gallon size Ziploc bag works fine), being sure that the sides of the bag don’t touch the plant. Mist whenever the soil feels dry. The cutting should root after one to two months. Once it does, remove the plastic and move it to a window. By the next spring, you should be able to plant the cutting outside.