Bartlett on Gardening: It’s All About Roots

October 21, 2017


llustrations from the Tennessee Master Gardener Volunteer Handbook.


Fall is a great time to plant trees and shrubs. The plants put their energy into forming a firm foundation for future growth by establishing a sound root zone during the cooler months of the year. But before you plunk that sapling in the ground, remember: Planting a tree is the perfect example of needing a $100 hole for a $25 plant.


When selecting the place to plant the tree, keep in mind the mature size of the canopy. One does not want it tangled up in utility lines or scraping the roof. Drainage might also be an issue. If you suspect that the site is too wet, dig a hole a foot wide and a foot deep. Fill it with water. If the water drains in three to 12 hours, drainage is adequate.


If the site is covered by grass, remove it before planting. Most of a tree’s feeder roots are in the top six inches of soil. Not only will the grass compete with the tree for water and nutrients, but grass secretes a substance that inhibits tree roots. Think about it. There are few trees in vistas of the prairie, pampas or savannah; nor are there many meadows in forests.


 How much turf needs to go? The planting hole needs to be two to three times wider than the root ball, so that would be the minimum area to clear. A tree’s root zone goes out two times the height of the crown, so don’t hesitate to clear a bit more. (For tips on removing turf, review my column of Sept. 16.)


In order to determine the depth of the planting hole, you must explore the top of the root ball of containerized or balled-in-burlap trees. Their roots were pruned to fit them into the packaging. Pull back the soil to find the place where the roots flare out from the trunk. This structure needs to show at ground level. Explore a bit more to identify the first lateral root. Plant it no deeper than one inch. Slope the sides of the hole to provide room for growing roots.


Now it is time to place the tree in the hole. Remove any wrapping from the trunk. Remove containerized trees from the container before placing them in the hole. (I have consulted on a failure-to-thrive tree, only to find that it had been “planted” in the container!) If it is a bare-root specimen, make a cone of the backfill at the bottom of the hole to fit into the center of the roots, carefully fitting the roots around that support.


 For burlap-wrapped trees, remove all twine and pinning nails and fold or cut down the fabric at least a third of the way from the top of the rootball. Do not leave any burlap exposed to the air where it might wick away moisture from the roots. Backfill halfway and water. Finish filling the hole and water again. New trees need six to eight gallons of water per inch of trunk diameter per week.


Do not amend the backfill soil. The roots need to venture into the native soil rather than remain in a compost-rich cocoon. Do not fertilize the tree unless a soil test indicates a specific nutrient deficiency. If you want to pamper the tree, apply organic matter over the anticipated area of the root zone at a rate of 50 pounds per 100 square feet and incorporate it into the soil to a depth of six inches.


The final step is to place two inches of organic mulch at least three feet around the tree. Shredded bark or bark nuggets are ideal for this purpose. Keep the mulch away from the trunk to prevent fungi and rodent damage. The mulch barrier protects the tree from mower and string trimmer injury while reducing competition from weeds and grass. It replenishes nutrients, retains soil moisture and buffers temperature extremes. 

​​Staking is generally unnecessary if the tree can stand in a moderate wind. A large tree may need staking the first year. All stakes should be removed after that time.


Trees are a long-term investment in the landscape because they take years to reach maturity. It is well worth the effort of digging a $100 hole to ensure they live a long, healthy life.



Master gardener Ann Bartlett never lets lack of familiarity with a plant stop her from trying it in the ornamental beds around her home.

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