How to water plants easily
Don’t kill your plants. This will make watering easier.
problem solved
Editor’s note: Throughout the growing season, Mike Hogan, OSU Extension lecturer in agriculture and natural resources in Franklin County, will answer questions from Dispatch readers about gardening and landscaping. Send your questions to [email protected].
Q: I need to prune an arborvitae hedge because it’s too tall. I want to remove 3 to 4 feet from the top of these shrubs. When is the best time to prune?
A: Late winter or early spring is generally the best time to prune conifers (evergreen conifers) such as arborvitae, but these plants do not respond well to heavy pruning at any time of year. Removing such a large portion of these plants will result in a permanent bare spot on the plant.
Once the foliage is removed, it will not grow back, even if the cuts now allow sunlight to get inside. Unlike broadleaf evergreens like boxwood or holly, coniferous evergreens do not have dormant buds on the older trunks waiting to grow when the branch or foliage behind them is removed. This is why deer damage to arborvitae is so visible, damaging and permanent.
Ask the expert: What is the best way to stop Japanese beetles from eating plants?
Shortening the height of a tall arborvitae will stunt the growth of the upper parts of the plant and result in a permanently flat top. This can cause stress to the plant and make it vulnerable to insect or pathogen invasions or a general decline in its vigor.
A better approach might be to remove the existing arborvitae and replace it with a smaller conifer. There are many compact and dwarf conifer species on the market today. There are also other conifers such as yews that can regrow after heavy pruning.
Q: We have three large blue spruces in our yard, and over the years each of them has developed dead branches in different places. One of these trees was completely dead, so we removed it. Is there any way to save the other two trees?
A: Colorado Blue Spruce (Picea sylvestris) is native to the mountains of Colorado. Over the past half century, this tree has become popular with homeowners, landscapers, and even Christmas tree growers in Ohio for its distinctive blue-green color and conical shape. Unfortunately, because they are native to the West, they are adapted to drier climates with more wind and cooler temperatures, conditions that are not typical in much of Ohio.
Recently, we have seen a frequent decline in blue spruce trees in Ohio due to various insects, pathogens, and environmental conditions. While blue spruce is attacked by insects such as bagworms, black vine weevils, and spruce spider mites, much of the damage we see on blue spruce in Ohio is due to a fungal pathogen called Rhizosphaera. This fungal disease typically attacks the lower branches of the tree first and eventually spreads throughout the tree, causing it to slowly die over several years.
If detected early, before entire branches have died, trees infected with Rhizosphaera respond well to treatment with a fungicide containing chlorothalonil. Complete control may require two applications of a fungicide in two or three consecutive years. The first application should be made immediately after growth emerges in the spring, followed by a second application three to four weeks after the first application.
Improving the environment around the trees can also help. Improving air circulation through proper spacing when planting or removing the lower branches of the blue spruce can also help reduce the incidence of the disease. Removing infected needles from under the tree can also prevent further infection.
Ask the expert: What do the little bumps on the oak leaves mean?
Q: Should a rain garden be watered when there is little rainfall? The plants in our small rain garden are turning brown this summer.
A: Most plants require soil moisture to grow – for photosynthesis, for cooling, and to transport minerals and nutrients from the soil to the plant. Plants in a rain garden are no different and require supplemental water during periods when there is no rain.
We have a large rain garden on campus that we recently started watering because the perennials like cardinal flowers, asters, irises, and others were wilting and turning brown due to lack of soil moisture. Trees and shrubs planted in a rain garden can usually thrive without additional irrigation during drought, but perennials with their smaller root systems definitely benefit from additional irrigation.
