Get Your New Tree Off to A Great Start

by Bill Vander Weit, Forestry Supervisor, City of Champaign, Illinois

Another Planting Season is Upon Us.

Unfortunately, many trees that are planted are destined to an early death for one simple reason – they have been planted too deep.

The improper planting of trees has been so widespread that one observer termed it a “national epidemic.” Researchers at the Bartlett Tree Research Laboratories excavated 363 trees planted over a two-year period and found that 93% had either excessive soil or mulch covering the root collar. The root collar is the area where the roots meet the trunk, commonly identified by a flaring of the trunk. Many of these trees planted in this manner will not survive for more than two years, though some will survive in a weakened state for 15 to 20 years before they exhibit decline symptoms.

Why are trees planted too deep? The simple explanation is that people do not know where the roots are. This problem can be traced back to the nursery. When cultivating between rows, nurseries often build up soil around the trunk. When nurseries transplant trees, the root collar can be buried, sometimes as much as six to nine inches. The buried root collar “suffocates” from excess soil, resulting in a disruption of water and nutrient uptake, starting a downward spiral for the tree.

How can one ensure that trees are not planted too deep? First, do not follow the common recommendation of planting a tree at the same depth it was growing in the nursery. When planting balled and burlapped (B&B) trees, this means exposing the root collar by removing excess soil using a small tool such as a putty knife or hand trowel. This can be done in most cases without removing the twine attached to the trunk, in an effort to keep the soil ball reasonably intact (figure 1). Current standards recommend that the root collar should be even with the soil surface, or in some cases 1-2 inches above grade (figure 2).

When purchasing trees from nurseries, let experience be your guide and buy from nurseries that pay attention to proper root collar depth. Don’t assume the root collar is at the top of all root balls. If root ball coverings are not removed and the root collar exposed, planting will have been done incorrectly. Figure 3: The white line on the trunk indicates the height of the soil ball. This tree was planted without removing the burlap or any excess soil, with the finished grade at the white line. The tree died the same year it was planted.

Following planting, new trees should be mulched with a 2-4 inch layer of organic mulch, taking care not to pile the mulch against the trunk.

Published in the Spring/Summer 2003 issue of Illinois Trees a quarterly publication of the Illinois Arborist Association.

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