Junipers could be facing transplant shock
Q uestion: Are “Blue Arrow ” junipers susceptible to wind damage? I planted some recently and they appear to be suffering.
Most evergreens are susceptible to some degree to desiccation from drying winds, but in our region, this type of desiccation typically occurs during the winter months. And, winter damage from drying winds is more common on broad-leaved evergreens, such as rhododendrons, hollies, laurels and boxwoods, than it is on needled evergreens like junipers. Plus, “Blue Arrow” junipers are hardy down to -30 degrees F, leading me to doubt that your issue stems from wind damage.
Since your “Blue Arrow” junipers were planted recently, I suspect the problem is a combination of transplant shock and improper watering, rather than wind desiccation.
Many evergreen trees and shrubs will suffer from a small amount of transplant shock within a few months of planting. However, the main symptom of transplant shock is the yellowing and loss of a small amount of needles toward the center of the plant. The newer, outermost growth typically remains unaffected. If you’re seeing yellowing and needle-drop all over the plant, it’s likely to be a sign of a bigger problem.
Too much or not enough water
Over- or under-watering is another common problem with newly planted evergreen trees and shrubs like your “Blue Arrow” junipers. It’s tough to know how much irrigation water is too much and how much is not enough. The symptoms of under- and over-watering are very much the same. If the roots of your junipers are sitting in a pool of water at the bottom of their planting holes, the needles will yellow and drop. The same thing will occur if the plants don’t receive enough water.
While you didn’t mention your watering habits since planting the junipers, I will say that under-watering is far more common than over-watering. Though we’ve had plenty of rainfall this autumn, the rain may not have percolated all the way down to the root zone. I suggest digging down next to the root ball about 12 inches and see how moist the soil is. Newly planted shrubs that were in a 3-gallon container at planting time need about 6 to 8 gallons of water per week, applied in one or two watering sessions. Larger pots or balled-and-burlapped shrubs need about 8 to 10 gallons per week in one or two applications. Apply the water slowly so it has the chance to soak in.
As the plants become established over the course of the following year, you can start to cut back on the irrigation by increasing the amount of time between waterings, not by reducing the amount of water added at any one time. Keep adding the same amount of water each time you irrigate, just don’t do it as frequently.
Eventually, trees and shrubs should be completely weaned from supplemental irrigation, except in cases of extreme drought. It takes at least a year for newly planted shrubs like yours to grow a root system extensive enough to access their own water. As they grow, you’ll need to provide them with the water they need.
If you dig down to the bottom of the planting hole and find a pool of water, you’re either over-watering or the site isn’t suitable to plants that can’t tolerate wet soils. Low-lying areas that frequently flood, sites with heavily compacted soils that are poorly draining and landscape areas where standing water collects are not good places to plant trees and shrubs that don’t like “wet feet.” Thankfully, there are plenty of plants that do like “wet feet” that would be a much better choice for those areas.
It will take a bit of sleuthing to determine exactly what’s happening with your “Blue Arrow” junipers, but doing so will save you from other potential troubles down the line.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to firstname.lastname@example.org or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.