Extension Educator, Horticulture
Some "rules" of life come back to haunt us …finish all the food on your plate; a nice tan is healthy; that bathing suit really does look good - it's just the mirror; and plant trees as deep as they were in the pot.
Trees are a long term investment, mentally, physically and financially. Our first step to healthy trees is making sure they are planted correctly. Trees may fail to thrive more often due to poor planting than to insects and diseases.
It seems simple. Dig a hole the size of the rootball and place the tree in the hole green side up. The problem is many trees are purchased with extra soil piled over the root system covering the root collar (the area where the roots meet the trunk identified by the trunk flare).
The extra soil can be traced back to common nursery practices. When cultivating between rows, nurseries often build up soil around the trunk. When the trees are transplanted the root collar will be buried sometimes as much as 6 to 9 inches.
Bill Vander Weit, City Forester for the City of Champaign, shared his concerns about trees planted too deep. "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."
These trees will probably not survive for more than two years though some will survive in a weakened state for 15 to 20 years until some other stress such as drought kills them.
Planting too deep is also likely the cause of girdling roots and nuisance root suckers.
As you are adding trees to your landscape this spring, follow these steps to ensure proper tree planting:
With balled and burlaped trees, remove the twine around the trunk, peel the burlap back and remove if possible. Snip off wire baskets if present then gently scrape away excess soil to reveal the root collar. When planted at the proper depth the root collar (trunk flare) should be visible. If the trunk enters the ground as straight as a telephone pole, the tree has been planted too deep.
Dig the hole as deep as the excavated root ball and no deeper so the soil under the root ball is undisturbed. Good news since you won't have to dig as deep a hole.
Dig a hole 2 to 3 times as wide as the root ball. This will allow roots to grow more easily into this area. The hole should look more like a saucer then a burial plot.
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.
Prune only broken or dead branches at planting time. Removing live branches removes a source of stored energy important in overcoming planting stress.
Stake trees only when needed as in windy or high traffic areas. Wire even if protected with garden hose can damage the trunk. Use broad-banded materials such as strips of landscape fabric, check frequently and remove after one year.
Wait a year to fertilize unless using a slow release fertilizer.
Add 3 to 4 inches of mulch such as wood chips. Mulch should not contact the trunk.
Do not wrap trees during the growing season. Wrap can hold moisture next to the trunk and serve as a home for insects.
Do homework first by selecting the proper tree. Avoid the "it's so pretty" impulse purchase. Select a tree with the correct mature height and one that will easily adapt to the soil and planting site.
Be sure to check with your city before planting any trees on the city right-of-way. Champaign and Urbana require permits before planting.