TREES and TURF – How to make the two of them work together! (part 2 – final)

The International Society of Arboriculture publishes in its tree care website the following guidelines on planning for a beautiful, valuable landscaping for all needs. At ABOVE AND BEYOND – TREE SERVICE we can help you planning your next tree project!  Contact us if you have any questions!

Maintenance Practices

Maintenance practices for trees and turf are different. Because tree and grass roots exist together in the upper 6 to 8 inches of the topsoil, treatment of one may damage the other. Fertilizer applied to one plant will also be absorbed by the roots of a nearby plant. Normally that is good, but excessive fertilization of either trees or turf can result in tree crown or grass blade growth greater than desired.

Many herbicides or weed killers that are used in turf can cause severe damage to trees when misapplied. Misapplication can occur on windy days, causing the drift to fall on nontarget plants, or on hot days when the herbicide may vaporize and diffuse into the air. While most herbicides do not kill tree roots, some, such as soil sterilants and a few others, do. Herbicides that can cause tree damage have statements on their labels warning against using the product near trees.

Watering of lawns is beneficial to trees if the watering is done correctly. Trees need, on average, the equivalent of one inch of rain every seven to ten days, depending on the species. Tropical rain forest trees may require more. Frequent, shallow watering does not properly meet the needs of either trees or turf and can be harmful to both.

Turf growing under or near trees should be mowed at the top of its recommended mowing height. Mowing off no more than one-third of the grass blade’s height and letting the clippings remain on the lawn does much to ensure a healthy and vigorous lawn. In an ideal situation, tree and turf maintenance would be handled by the same individual in order to maximize the benefits of all maintenance practices.

Special Situations

  • Placing fill dirt around existing trees. Fill dirt frequently is added around existing mature trees so that a level or more visually desirable lawn can be established. Fill dirt changes the ratio of oxygen to carbon dioxide around tree roots and the roots may subsequently die. Consult a tree care expert before adding fill or constructing soil wells around tree trunks.
  • Establishing lawns around existing trees. Preparation of a seedbed for lawns requires disruption of the upper 4 to 6 inches of topsoil. This soil contains the feeder roots of trees. Damage to tree roots often results in declining tree tops.
  • Lawn watering in arid sites. Homes are sometimes built in woodlots. In arid regions, the watering that is required to maintain grass is especially damaging to dryland trees. Excess water at the tree trunk encourages growth of fungi that can kill trees.

Thin turfgrass growing around trunk-scarred weak trees does not need to be a common sight in the landscape. With proper planning, proper plant selection and placement, and reasonable management, the many and varied benefits of both trees and turf can be readily achieved.

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