By Katie Drewitz, U of M Extension
Trees provide many things for our communities: beauty, energy conservation, reduction of soil erosion, filtering air pollutants, raising of property values, a home for wildlife, and so much more. Trees are an integral part of our home landscapes and neighborhoods. If you are looking to plant a tree for Arbor Day or anytime this year, there are a few things you will want to keep in mind.
The most common mistake when planting trees today is planting too deep. Many trees we purchase have the root collar buried in the root ball. If this excess soil is not removed, the root collar “suffocates” from excess soil resulting in a disruption of water and nutrient uptake, starting a downward spiral for the tree. It can also result in the tree roots wrapping around the trunk and eventually girdling the tree. The root collar is the area where the roots meet the trunk, commonly identified by a flaring of the trunk. To ensure your tree is not planted too deep, do not follow the common recommendation of planting the tree at the same soil level that it currently has. You may need to remove 6-9 inches of soil until you find the root collar. Then, make sure the bottom of the collar is at ground level. If the trunk enters the ground as straight as a telephone pole, the tree has been planted too deep.
When digging your hole to put your tree, dig the hole as deep as the root ball and no deeper so the soil under the root ball is undisturbed. This will prevent the tree from settling. Dig a hole two to three times as wide as the root ball. This will allow roots to grow more easily into this area. Do not add soil amendments. Old recommendations for adding soil amendments such as peat moss have been discarded. Simply use the soil removed from the hole as backfill.
Watering a newly planted tree is extremely important to ensure that it establishes and stays healthy for years to come. Your tree may need watering for longer than you realize. Newly planted trees need to be watered daily for the first 2 weeks, 3 days a week for next 12 weeks and once a week until the roots are established. You can figure out how long it will take for the roots to establish and how much water your tree needs at each watering by measuring the trunk caliper. For a tree with a caliper less than 4 inches, take the measurement at 6 inches above the ground. For a tree whose trunk caliper is greater than 4 inches, measure at 12 inches above the ground. For each inch of trunk caliper, your tree will take 1.5 years to establish and 1.5 gallons of water at each watering.
You may want to add some wood chips or other mulch around the base of your tree to make mowing easier. Mulch should not contact the trunk; meaning that it should not look like a volcano at the bottom of your tree. Mulch helps to conserve soil moisture and eliminates competition from turf. However, if it is mounded up and in contact with the trunk it will ultimately cause more issues than it fixes. Excessive amounts of rock or landscaping rocks can also be detrimental around the base of the tree.
Do not wrap trees during the growing season. Wrap can hold moisture next to the trunk and serve as a home for insects. Some wraps can also cause sun damage to the trunk of the tree which is harmful.
Finally, be sure to consider the tree’s mature height and breadth when choosing its planting location. You would hate to need to remove your tree in a few years because it is too close to your house or growing into a powerline.
Properly planted and cared for, trees can last a lifetime. If you have questions about this or any other horticulture topic, please reach out to local Extension Educator. Residents of Stearns, Benton, and Morrison Counties can call (320) 255-6169 ext. 1.