Juniperus conferta or Juniperus rigida subsp. conferta, is a resilient coniferous shrub, characterized by its needle-like blue-green leaves which present in clusters, creating dense, prickly foliage. Its robust nature allows it to thrive in coastal regions, where it often forms wind-swept mats. The plant’s distinct cones, small and berry-like, attract a variety of wildlife, serving as a valuable food source.
I. Appearance and Characteristics
Juniperus conferta (shore juniper and blue pacific juniper) is a species of juniper, native to Japan, where it grows on sand dunes. It is often treated as a variety or subspecies of Juniperus rigida.
Conferta is derived from Latin. “Con” meaning together and “ferta” meaning strong.
This plant type can grow up to 6-18″ tall with creeping stems as wide as 8″. The awl-shaped, aromatic foliage on branched stems features pointed blue-green needles in groups of three.
Ground cover juniper also bears fruit. It produces berry-like seed cones that take on a silvery bloom upon maturity. The plants are sun-lovers and thrive well in medium moisture and well-drained, dry soil. Birds tend to enjoy munching on these berries.
The plant originated in Japan, where it grows as an evergreen shrub on the Pacific ocean side. It has spread to Russia and is also present in varying parts of the US due to its use in home gardens. There are established cultivars that work well in any ground cover situation.
II. How to Grow and Care
Light and Temperature
Juniperus conferta requires full sun and grows well in USDA zone 6-9. The plant should be grown in a well-lit area where it can get 6 to 8 hours of full sun throughout the day. If you’re growing in a different zone, pay attention to care requirements ahead.
The plant thrives in a wide range of temperatures but is sensitive to those below -10°F. While it may return in the spring following a sub-freezing winter, it may need some help from a frost blanket in these conditions.
Water and Humidity
As a drought-tolerant plant, the Shore Juniper survives well in dry, arid environments. It only requires medium moisture. Overly wet soil can cause the branches to die or turn brown. Give the young plants deep watering 2-3 times a week in the first month. Once the plants mature, give them deep watering of about 1 inch per week to retain their green growth.
Allow the soil to dry between waterings. Constantly wet soils, or even slightly overly wet soils can provide conditions where root rot can thrive.
Soil
This species thrives well in well-drained, dry, and sandy soils. It can tolerate acidic and neutral soils but grows especially well in slightly alkaline soils with pH 8-8.5. If the soil you’re working with is not a sandy type, well-draining soil works. Try not to add too much organic matter to the mix, as this can increase water retention and may make the soil too wet.
Fertilizing
Evergreen ground covers don’t need much fertilizer. However, you can treat Juniperus conferta (Shore Juniper) with a complete fertilizer like 12-4-7 or 16-4-8 in early spring and late summer. Dilute to half-strength and do not fertilize in fall and winter.
Planting Instructions
To transplant, dig a planting pit with a layer of 4 to 6 cm organic manure on the bottom as the base fertilizer. Next, add a layer of soil on top of the manure to avoid the juniperus rigida subsp. conferta roots coming into direct contact with the fertilizer, so the highly concentrated fertilizer doesn’t dehydrate the roots. Place the plant into the pit, backfill the soil to fully cover the roots, and press the soil firmly. Water thoroughly.
Pruning
The best time to prune the plants is late winter to early spring, just before new growth begins. Prune the dead branched stems beneath the canopy of the plant to improve air circulation. Don’t try to prune to reduce the size of the shrub. Instead, move it to another area if it is an obstruction. Trimming isn’t effective on juniper shrubs.
Propagation
Juniperus conferta can be propagated by using juniper cuttings. Take healthy branches and cut up 8-10″ long stems. Dip the cuttings in rooting hormone and stick them into a well-prepared planter. Lightly mist the potting mist till it’s moist. Place the planter under indirect sunlight at 60-65°. Mist the cuttings daily and pull up on the plant gently to check for root development every 4 weeks.
Pests and Diseases
- Common Problems
There are few growing problems you may encounter with your conferta. You might run into improper planting or planting in an area with too much shade or water. If this is the case, move the shrub to an area with well-draining soil, and full sun.
- Common Pests
The plant is quite susceptible to aphids, bagworms, twig-borers, and webworms. Bag worms create a carapace from dried juniper leaves. Twig borers are metallic blue beetles with long antennae. They bore into the juniper stems and trunk, and cause sections of the canopy of awl-shaped leaves to yellow and die off. Webworms are caterpillars that spin dense webs around parts of the branches as they feed.
Start treating these by pruning damaged areas in early spring. If you’re not concerned about potential harm to wildlife, use insecticidal soap, neem oil, or a strong horticultural oil to ward off the pests from the plant.
- Common Diseases
To fight fungal blights, the application of a copper fungicide or chemical fungicide should handle most of the problem, but you will need to prune off already-infected material. Bacterial blights can be treated by copper fungicide as well but with a slightly-less-effective outcome. In order to prevent rust diseases, apply sulfur fungicide or copper sprays to destroy the infection on the susceptible plants. For effective results, spray at the first sign of disease.
The main problem with junipers is root rot. They are not tolerant to water-logged soil, which can easily lead to the development of fungi that cause root rot. Make sure to have well-draining soil, plant it in full sun, and water when necessary. Remember, all of these treatments can affect wildlife in a negative way. Use them with caution.
Overwintering
Although juniperus rigida subsp. conferta is quite cold-resistant, young and newly-grown plants need protective winter measures. It’s best to cover the plants’ roots with hay, soil, or plastic film in the early winter, and paint their trunks white with water-based latex paint.
If not painted white, a dark-colored tree trunk absorbs heat from winter daylight, bringing the trunk temperature up. Then it drops drastically at night. When the temperature difference between day and night gets too big, the bark could fissure, making the juniperus rigida subsp. conferta is more vulnerable to pests and diseases.
III. Uses and Benefits
Juniperus conferta is often grown as bonsai.
IV. Varieties
The Shore Juniper belongs to the genus Juniperus which is known for its blue-green, cascading branches. The most famous cultivars are Juniperus conferta ‘Blue Pacific’, ‘Sliver Mist’, and ‘Sunsplash’, although others like ‘Allgold’ and the subspecies ‘Schlager’ are growing in popularity.
‘Blue Pacific’ is slightly hardier than others, stands out for its blue-green foliage, and spreads wide as ground cover. Use conferta blue pacific to add accents to areas with well-drained soils. Conferta blue pacific is lovely punctuation in a retaining wall, too.
‘Silver Mist’ has a crowded, dense-growing habit and grows 16″ tall. It has beautiful, silvery blue-green foliage that develops a purplish cast in winters, as opposed to the blue-green of blue pacific. Plant it among yellow-flowering plants to offset its foliage.
Lastly, ‘Sunsplash’ is a variegated form of Juniper ground cover that, like conferta blue pacific, features bluish-green foliage. What differentiates it from conferta blue pacific is its gold-yellow needles. The foliage remains fresh in all seasons.
IV. Harvesting and Storage
When juniperus rigida subsp. conferta branches are harvested and placed in vases for viewing, they can last for 2 months. Early-morning harvest is best to avoid branches withering due to dehydration. Cut the branches off at a 45° inclined angle with a pair of sharp gardening scissors and quickly put them in clean water to prevent water loss.
Find Where to Buy the Best Shore Juniper (Juniperus conferta)
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