Now is a good time for fall tree care

By Nathan Winter
University of Minnesota Extension

Trees are often enjoyed more by people that come after those who planted the tree. Trees help define how a yard in the city will look and the type of landscaping that can be done by determining shade or full-sun types of plants. Businesses and city municipalities also use trees to help make areas more aesthetically pleasing to those who are working within, as well as those who are using those areas for recreation. In rural country settings, trees serve many purposes.

Trees are often used as a windbreak in prairie areas to catch snow and slow winds. Around structures, trees keep homes cool in the summer and warmer in the winter by protecting them. Often, trees are planted to help preserve the memory of a loved one, or the trees were planted by a loved one that has died.

With all of the positives, it is no wonder why people care so much about trees. Tree questions are very common at my office, as well as for tree care professionals. I have found that quite often those that care so much about their trees could better serve the trees by eliminating harmful practices.
We need to know when and how to plant trees to get them started off in the right direction.

According to the University of Minnesota Forest Resource Extension, in the Midwest region, bare-root trees and shrubs should be planted when the plants are dormant in the spring or at the end of the growing season (fall). Balled and burlapped, containerized, and container-grown plants can be planted throughout the growing season, but with caution during the summer months. If planting in the fall, the recommendation is to plant four weeks before the soil temperature drops below 40 degrees. To plant trees correctly, get a copy of the University of Minnesota publication, “Planting Trees in Minnesota,” from the University of Minnesota Extension Web site: www.extension.umn.edu or call most University of Minnesota Extension offices. The publication also has choices for proper Minnesota tree species.

Watering is going to be important to a newly planted tree as well as any existing trees on your landscape. Since watering is such a time consuming task, you may have to pick and choose the existing trees to water. I recommend watering any newly planted trees and also water any trees that have shown stress, disease or insect problems through the growing season.
Established trees should be watered around the “root zone” of the tree. Roots of trees can vary from one-and-one-half to three times as wide as the canopy. Avoid frequent light watering, and instead water infrequently and heavily. Wet the soil to a 6- to 8-inch depth and then let the soil dry out in between. Use a rod to determine when you have wetted the soil to that depth. Believe it or not, you can over water trees, which will starve the roots of oxygen and cause roots to rot. If fall rains are averaging one inch every week, watering will probably not be necessary. Generally, you want to have an adequate amount of moisture before the ground freezes up in late fall, especially with coniferous trees.

Protect stems of landscape and shrub trees from animals and mechanical equipment. This is most important on new or young shrubs and trees. Use a mesh or hardwire cloth at least three inches from the stem. Plastic guards can also be used, but they are only recommended to encase the lower part of the stem, where damage can take place. Sunscald can be prevented by wrapping the trunk with a commercial tree wrap, plastic tree guards, or any other light-colored material. Put the wrap on in the fall and remove it in the spring after the last frost. Wraps should be used primarily on new trees.

Fertilizing trees should be done on a case-by-case basis. A soil test can be done to determine if the soil does not contain adequate amounts of fertilizer. University of Minnesota soil test kits can be picked up at most University of Minnesota Extension offices. Often, the tree has sufficient amounts of nutrients available if the lawn is being fertilized regularly. If fertilizer is needed, a late fall application can be done before the ground freezes for coniferous trees. For deciduous trees, apply fertilizer between when it is fully leafed out and when it starts showing fall color change.
Pruning can also be done this time of year on many trees. Late fall until next spring is time when it is safe to prune oaks and elms. During the dormant season serious disease problems are less problematic. Hold off on apple trees until the best window for preventing disease spread, which is late winter (late-February to early-March). Another helpful publication is the University of Minnesota publication, “Pruning Trees and Shrubs” located on the Extension Web site or by calling most Extension offices. This publication is a good how-to guideline for pruning trees.

Do the best you can to educate yourself on caring for those beloved trees properly. Proper care will help increase the longevity of your landscape trees and give you and others years of enjoyment and admiration for the trees.

(Nathan Winter is an agricultural educator — McLeod and Meeker counties with the University of Minnesota Extension.)