( Blue Rug Juniper )
Plant taxonomy classifies Blue Rug juniper plants under Juniperus horizontalis. The cultivar is 'Wiltonii.'
Blue Rug juniper plants are low-growing evergreen shrubs and conifers. They are also dioecious.
This juniper can be grown in zones 3-9.
Foliage is a silvery-blue, thus the first half of its common name. The second half comes from its growth habit, as it forms a dense, low mat (rug) -- making it an ideal groundcover. Height 4"-6", spread 5'-6'. Foliage turns a purplish-bronze in winter. Blue Rug spreads rapidly and is relatively resistant to some of the diseases that plague juniper shrubs. Incidentally, what look to be blue "berries" on junipers are technically cones.
No plant is "no-maintenance," but this one is certainly "low-maintenance." Groundcovers that flower require much more care. Space 4'-6' apart to form a dense enough mat to crowd out weeds. To aid their weed-control efforts prior to maturity, make sure they're well mulched (but don't pile up mulch over the plants' crowns). Don't allow fallen leaves and branches to smother young plants. Thin out mature plants for better air circulation, which well help avoid disease; but don't prune severely.
Blue Rug juniper plants thrive in full sun and prefer well-drained soil with an acidic pH. Before planting, prepare the soil with amendments.
In addition to their use as groundcovers (see below), the juniper shrubs and their relatives make excellent specimens for rock gardens.
There are numerous types of junipers, and they come in a variety of heights, forms, colors (golds, blues and greens) and textures. But note that not all junipers are suitable for groundcovers. Some junipers are trees, while others fit the more usual image of "shrubs," i.e., plants that stand anywhere from knee-high to chest-high. Such plants are suitable for privacy screens and hedges.
But the focus of this article is the vine-like, low-growing junipers. Where and why would you grow such plants? Although they can be grown on flat land, juniper groundcovers are most prized as plants that can cover a sunny slope, where they serve 3 purposes simultaneously:
In addition, many other plants find it difficult to thrive on sunny slopes, where water runs off so quickly that the vegetation is apt to go thirsty. But juniper, on the contrary, tends to be relatively drought-tolerant and craves excellent drainage.
Many varieties besides Blue Rug juniper plants are suitable for groundcovers. A green cultivar of Juniperus horizontalis, namely, 'Prince of Wales,' purportedly grows even more quickly, while another cultivar, 'Mother Lode,' bears greenish-gold foliage. Meanwhile, the 'Pancake' cultivar stays smaller than these, both in terms of height (an amazing 2"-3") and spread (2').
Other species of juniper groundcover are Juniperus procumbens and Juniperus squamata. The 'Blue Star' cultivar of the latter provides another option for those who seek that cool blue foliage. But Blue Star will get taller over time (up to 3') than Blue Rug and doesn't spread as much, proportionately (4').
Low growing, evergreen with dense foliage and a uniform growth habit. Very flat growing form with trailing branches. Typically grows 4 to 6 inches by 6 to 8 feet with thick silver-blue foliage which assumes a light purplish hue in winter. Very fast grower. Female with 1/4 inch silvery blue cones. Good groundcover for large scale areas Excellent as a bank cover for erosion control. One of the most popular ground cover junipers in the U.S. and Europe. Does quite well in the heat of the South. From Maine.
Established plants can benefit from fertilization. Take a visual inventory of your landscape. Trees need to be fertilized every few years. Shrubs and other plants in the landscape can be fertilized yearly. A soil test can determine existing nutrient levels in the soil. If one or more nutrients is low, a specific instead of an all-purpose fertilizer may be required. Fertilizers that are high in N, nitrogen, will promote green leafy growth. Excess nitrogen in the soil can cause excessive vegetative growth on plants at the expense of flower bud development. It is best to avoid fertilizing late in the growing season. Applications made at that time can force lush, vegetative growth that will not have a chance to harden off before the onset of cold weather.
Full sunlight is needed for many plants to assume their full potential. Many of these plants will do fine with a little less sunlight, although they may not flower as heavily or their foliage as vibrant. Areas on the southern and western sides of buildings usually are the sunniest. The only exception is when houses or buildings are so close together, shadows are cast from neighboring properties. Full sun usually means 6 or more hours of direct unobstructed sunlight on a sunny day. Partial sun receives less than 6 hours of sun, but more than 3 hours. Plants able to take full sun in some climates may only be able to tolerate part sun in other climates. Know the culture of the plant before you buy and plant it!
Full Sun is defined as exposure to more than 6 hours of continuous, direct sun per day.
Normal watering means that soil should be kept evenly moist and watered regularly, as conditions require. Most plants like 1 inch of water a week during the growing season, but take care not to over water. The first two years after a plant is installed, regular watering is important for establishment. The first year is critical. It is better to water once a week and water deeply, than to water frequently for a few minutes.
Dig a hole twice the size of the root ball and deep enough to plant at the same level the shrub was in the container. If soil is poor, dig hole even wider and fill with a mixture half original soil and half compost or soil amendment.
Carefully remove shrub from container and gently separate roots. Position in center of hole, best side facing forward. Fill in with original soil or an amended mixture if needed as described above. For larger shrubs, build a water well. Finish by mulching and watering well.
If the plant is balled-and-burlapped, remove fasteners and fold back the top of natural burlap, tucking it down into hole, after you've positioned shrub. Make sure that all burlap is buried so that it won't wick water away from rootball during hot, dry periods. If synthetic burlap, remove if possible. If not possible, cut away or make slits to allow for roots to develop into the new soil. For larger shrubs, build a water well. Finish by mulching and watering well.
If shrub is bare-root, look for a discoloration somewhere near the base; this mark is likely where the soil line was. If soil is too sandy or too clayey, add organic matter. This will help with both drainage and water holding capacity. Fill soil, firming just enough to support shrub. Finish by mulching and watering well.
Caterpillars are the immature form of moths and butterflies. They are voracious feeders attacking a wide variety of plants. They can be highly destructive and are characterized as leaf feeders, stem borers, leaf rollers, cutworms and tent-formers.
Prevention and Control: keep weeds down, scout individual plants and remove caterpillars, apply labeled insecticides such as soaps and oils, take advantage of natural enemies such as parasitic wasps in the garden and use Bacillus thuringiensis (biological warfare) for some caterpillar species.
Leaf Miner is actually a term that applies to various larvae (of moths, beetles, and flies) that tunnel between upper and lower leaf surfaces, leaving a distinctive, squiggly pattern. A female adult can lay several hundred eggs inside the leaf which hatch and give rise to miners. Leaf miners attack ornamentals and vegetables.
Prevention and Control: Keep weeds down and scout individual plants for tell-tale squiggles. Pick and destroy these leaves and take advantage of natural enemies such as parasitic wasps. Know the Growing Degree Days (GDD)* for your area to target insecticide sprays when most beneficial for controlling the specific leafminer. Seek a professional recommendation and follow all label procedures to a tee. *GDD numbers should be available from your local Cooperative Extension office.