Karl Foord, UMN Extension Educator
If you purchased a tree and planted it at the soil line as it was in the pot, it is likely that this tree was planted too deep - with drastic consequences. Research conducted by Gary Johnson, Jeff Gillman, and Chad Giblin has shown that trees planted too deeply tend to generate roots that can strangle the plant. Dr. Jeff Gillman explains more of the science in the following article; however in this article I want to address what I believe is the true cost of making such an error.
I have two 'Autumn Blaze' maple trees that were planted approximately 10 years ago. Several years ago I checked the planting depth of the trees and discovered that one had been planted too deep (tree 1). Tree 1 had several encircling roots that severely impacted its growth (Photo 1). Tree 2 had a few encircling roots that I caught before much damage was done (Photo 2). What is the result? The trunk diameter of tree 1 is 4" and the trunk diameter of tree 2 is 8". Tree 1 is @ 25' tall and tree 2 is @ 35' tall. Tree 1's leaves colored and dropped early. Tree 1 looks anemic next to tree 2, and I have concerns as to whether it will survive.
What is the true cost of this error? TIME! If this tree dies and needs to be replaced, it will be some 11 or 12 years behind the other trees. Even if it lives, it is essentially half the size of a tree planted at the same time. All for having planted the tree in the ground at the soil level as it was in the pot; a fairly reasonable assumption all things considered. I can buy another tree but I cannot gain back the 12 years. Plant your trees at the correct depth as noted in Dr. Gillman's article.