With a name like “Blue Star,” this juniper sounds as American as apple pie, but in fact, it is native to Afghanistan, the Himalayas, and western China. Gardeners love Blue Star for its thick, starry, blue-green foliage and its graceful, rounded habit. Read on for more information about Blue Star juniper (Juniperus squamata ‘Blue Star’), including tips on how to grow a Blue Star juniper in your garden or backyard.
I. Appearance and Characteristics
Try growing juniper ‘Blue Star’ as either a shrub or a groundcover if you live in an appropriate region. It’s a lovely little mound of a plant with delightful, starry needles in a shade somewhere on the boundary between blue and green. According to information about Blue Star juniper, these plants thrive in USDA plant hardiness zones 4 through 8. The foliage is evergreen and the shrubs grow into mounds some 2 to 3 feet (61-91 cm.) high and wide. You have to have patience when you start growing Blue Star, since the shrub doesn’t shoot up overnight. Once it gets settled in though, it’s a champion garden guest. As an evergreen, it delights all year long.
II. How to Grow and Care
Sunlight
Plant this small evergreen bush in full sun. Give it an open, sunny space with a reasonable distance from other herbaceous plants or large shrubs.
Temperature and Humidity
Having developed in the mountains of Asia, the Blue Star juniper will not do well in areas with high heat and humidity.
Watering
Make sure to water these dwarf evergreen shrubs properly during their first year in the yard so that they can become established, then let them go. Water established plants occasionally when they look dry, or more often in extreme heat, keeping in mind this plant doesn’t like overly wet conditions. They are relatively drought-tolerant shrubs once they mature.
Soil
Its natural preference is for light, sandy soil, but Blue Star juniper does well in various soil types, from slightly acid to alkaline (pH 5.0 to 8.0), as long as they are well-drained. It does not tolerate water-logged soil.
Fertilizing
You will only need to fertilize Blue Star juniper in the late winter or early spring of its first year. Use a general 10-10-10 fertilizer. For the amount to use, follow the product label instructions. Once established, it won’t need routine fertilization. Fertilize your plants by applying compost to the soil.
Planting Instructions
Plant new shrubs in a shallow, broad hole as deep as the root ball and three times as wide. Add some compost to the soil and replace the soil up to the base of the plant. Give the new plant a good watering. Cover the ground around it with a 2-inch layer of mulch, but keep it 4 inches away from the stem. Water new plants weekly during the first growing season.
Pruning
Their slow growth rate means that Blue Star juniper shrubs hardly ever have to be pruned unless you try to fit them into an area with very little room.
One thing to be aware of is that this plant can experience a sudden growth spurt following several years of no significant increase in size. So it might happen that it perfectly fits into a tight spot without any need for pruning for a long time, and then it may sneak up on you size-wise and will require pruning.
Propagation
Because Blue Star is a cultivar, the only way to propagate a plant true to type is the vegetative way, through stem cuttings, and not through seeds. Here’s how it’s done:
- Cut off a healthy stem at least 5 inches long using a sharp knife or pruner in late fall or winter. Remove any side shoots and the needles from the lower portion of the stem.
- Fill a 4-inch pot with potting mix and dip the cut ends in rooting hormone. Make a hole in the soil with a pencil or stick and insert the cutting. Water well until the soil is evenly moist.
- Place the pots in a protected outdoor location, such as a cold frame with bright, indirect light. Keep it evenly moist.
- In the spring, repot any rooted cuttings in larger individual pots. Let them grow in the pots for a couple of seasons. The stronger they are when transplanted, the better their chance of survival in the landscape.
Potting and Repotting
To grow Blue Star juniper in a container, choose one at least 8 inches wider than the nursery container, so it has room to grow for at least two to three years before requiring repotting. The preferred container material is terra-cotta, so the container does not topple over easily.
Like all container plants, Blue Star grown in a pot needs more frequent watering than when grown in garden soil, especially during hot summer.
Overwintering
Blue Star is a hardy evergreen that can tolerate winters up to USDA zone 4 without protection. Potted plants, however, need to be moved to a sheltered outdoor location. The containers should also be insulated as the roots don’t have enough soil around them to protect them from the winter cold. You can winterize the container by wrapping the container in burlap or bubble wrap.
Pests and Diseases
Blue Star juniper is a tough shrub mostly unbothered by pests and diseases when planted in well-drained soil. Soggy soil can lead to root rot. Any disease or bug-pest problems will generally occur on these shrubs only in hot, humid regions.
One such problem is spider mites. When you first detect spider mites, hose the bush down with a powerful spray. This may knock the pests off. Check your bush regularly after that to ensure that the spider mites do not return. Repeat the hosing-down as needed.
Deer do not eat Blue Star junipers (probably because the foliage is so bristly), making them a deer-resistant shrub.
III. Uses and Benefits
As dwarf shrubs, Blue Star junipers are adequate specimens for tiny spaces, such as plantings for narrow patio areas or foundation beds. They can be used as edging plants or ground covers for larger areas. These plants can also be grown in containers.
