University Extension experts helping homeowners keep trees healthy

Trees in lawns require different care than grass

7/13/2011 - By: Wendy Hanson Mazet
Shallow watering means shallow root systems. Allowing your trees to only get water from your lawn sprinkler system could lead to a shallow root system and an unstable tree.

Nevada homeowners who have trees growing in their lawns have to take special precautions to make sure their grass and their trees thrive in an environment to which they are adapted.

According to University of Nevada Cooperative Extension Master Gardener coordinator Wendy Hanson Mazet, trees and grass often compete with each other, which can result in an unattractive and unhealthy landscape.

"When it comes to caring for your trees in lawn, knowledge of both their growth requirements will help you to provide an environment in which they can thrive," Mazet said. "Remember to water the trees deeply and less frequently to encourage roots to grow deeper and decrease the amount of competition between grass and tree roots. Also, eliminate lawn under the canopy of trees to further reduce competition."

Mazet noted that eliminating grass from beneath your trees will reduce the damage that can be done by a mower or weed-eater. And forcing your trees to get all their water from the lawn sprinkler system can result in lawns ridden with with surface tree roots, and trees and grass both declining from drought stress.

Here are some other tips for helping your trees and grass co-exist happily:

  • Occasionally water your trees with a slow steady supply that allows the water to seep deeply into the soil, encouraging a tree's root system to spread downward. This deeper root system will make your tree healthy and sturdier in high winds.
  • Mow your lawn to no less than 3 inches in height. This will help it survive the heat of summer. Most homeowners, Mazet said, water their turfgrass frequently and to a shallow depth, which encourages dense masses or roots and a thick layer of thatch.
  • When placing a tree in your lawn, make sure you put the "right tree in the right place." Research the tree's characteristics. For example, a Little Leaf Linden has potential to be 30 to 45 feet high and 20 to 30 feet wide. It is a hardy tree for this area with a cold hardiness rating of USDA Zone 3, and is used as a specimen tree in parks and boulevards. Its relatively small size works well for areas with limited space.
  • Trees should be transplanted into a hole no deeper than the soil in which they were originally grown. The width of the planting hole should be at least three times the diameter of the root ball or container. When planting from a container, the roots are generally root-bound and should be gently pulled outward away from the center. This will allow the roots to grow out into the landscape soil. Backfill the hole with native soil, with compost added to the top six inches to encourage healthy soil biodiversity.
  • Hand water established trees once a week; twice a week for newly planted trees. Watering times will vary on soil texture and water absorption. Do not keep soil muddy as overwatering can smother the roots and kill your tree.
  • During the hot summer months, neither the turfgrass nor the trees need high doses of fertilizer because the heat slows their growth. Remember, any product you apply to your grass will affect your trees in, or adjacent to, the lawn. Be cautious with Weed-n-Feed-type products because the active ingredient in them that kills dandelions in your lawn could also kill your tree.

For more information on keeping your turfgrass and trees healthy, contact your local University of Nevada Cooperative Extension office. Wendy Hanson Mazet is the Master Gardener Coordinator for University of Nevada Cooperative Extension. She can be reached at hansonw@unce.unr.edu


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