Caring for Conifers
Conifers, made up primarily of spruce, fir, pine and hemlock, are an attractive and long-lasting addition to any landscape. Conifers naturally provide the bonus of evergreen color, which can serve as a backdrop or simple visual relief in a stark landscape. Conifers can be used in a number of creative ways as hedges and in rock gardens. So how do you get started planting and working with conifers?
Robert Childs, of the University of Massachusetts Extension Service, shares his knowledge on how best to care for conifers.
Before You Buy
Childs said the first thing you want to do is find a reputable nursery. Second, you want to have your soil tested. “Everybody forgets about the soil,” said Childs. “Most conifers prefer a soil that is slightly acidic,” he said. Childs said that conifers, when they do drop their needles, help to provide needed soil acidity without overwhelming the tree.
Also, be sure you know what planting zone you are in. For example, Massachusetts is a Zone 5. Conifers that would thrive on Long Island, NY (Zone 7), would not be able to tolerate the level of cold in Massachusetts. Here is a link to the UDSA Zone Map.
“Every tree has its own set of needs,” said Childs. “Plant the right tree in the right place.”
Childs also said that a basic rule of thumb about conifers is that most do not like wet soils. Research the type of conifer you want to plant. Childs gave the example of the salt sensitivity of White Pines. “You wouldn’t want to plant them next to a major road or the salt run-off in the winter will kill them. Whereas the Pitch Pine you’ll find on the Cape (Cape Cod) is very salt tolerant,” he said.
Tips When Planting Conifers
“Trees that are transplanted are under stress for up to two years. You can’t just plant them and walk away,” said Childs. Childs said that the most important factor in transplanting conifers is how the root system is cared for. “Large nurseries may be digging up tens of thousands of trees with machinery. Some trees may not come out with a healthy root system,” he said. “You want to have maximum root development. Trees loose up to 95 percent of their roots when being transplanted.”
Childs said that the fall it is best time to transplant conifers. Once you have your trees ready for planting, take the burlap, wire, or bucket off of the plant and examine the roots. Plant the tree only up to the root flare. The root flare is what it sounds like, where the roots begin to flare out. Childs said that if you plant the tree above the flare, it will likely kill the tree. He added that most people expect to be able to just take the burlap or bucket off the root ball and just drop it in the ground. “Sometimes the flare ends up in the middle of that root ball,” said Childs. “Take off as much wrapping as possible and really examine what you have.”
Make sure your conifers receive adequate water following planting, especially when there is a drought.
Childs said that “unless its incredibly poor soil, you shouldn’t have to use peat, compost, or manure to fertilize.” Childs recommended that only in the worst soil conditions should a fertilizer such as a 10-10-10 mix be used.
What insects are conifers susceptible to, and what do I do about them?
Conifers don’t tend to be especially attractive to insect infestations with a few notable exceptions. Mugo, or dwarf mountain pines, are susceptible to caterpillar infestations. Mugo pines are often used as ornamentals around rock gardens as they are low-lying. Some conifers are susceptible to pine needle scale and spider mites, and hemlocks may attract wooly adelgid, which was introduced to the northeastern US in the 1950’s.
Wooly adelgid are fluid sucking insects similar to aphids. “It has weakened a lot of trees and can kill them,” said Childs. Do not fertilize with nitrogen-containing products if you have wooly adelgid, as they thrive on nitrogen.
There are many pesticides approved for homeowner use, some of which are earth-friendly such as horticultural oils and insecticide soaps. However, you may want to call in a professional if the problem gets out of hand. You also may need to take out any diseased/infested trees so that any others around them have a better chance for survival.
What about pruning?
Due to the fact that the conifers you are transplanting have been stressed by the process, you don’t want to do any heavy pruning initially said Childs. “You shouldn’t prune at planting unless you have broken or damaged limbs,” said Childs. “The foliage and roots ‘talk’ to each other via hormones.” He said the communication process that goes between roots and foliage on lets the tree know it needs more water or certain types of nourishment.
Now you have the basics on conifer care. Again, it is best to talk with people at local nurseries to find additional information regarding which conifers will work best in your location.