Selecting and Planting Trees

Bulletin 845

Caring for Established Trees

A tree is a living organism in balance with surrounding natural elements. Even when the plant has been properly selected, sited and planted, maintenance is required to ensure that trees continue to bring pleasure. The following cultural practices will help ensure plant health.

• Maintaining proper pH is critical for many trees. A pH of 6.0-6.5 is ideal for almost all plants. Sulfur is normally used to lower pH and ground limestone is used to raise pH.
• Fertilization is the addition of nutrients. Nitrogen is the element most likely to be deficient in Ohio. Remember that tree roots extend 11/2 to 3 times the height of the plant away from the trunk. Fertilizing lawns and shrubs also results in fertilizing nearby trees. Depending on the circumstance, between 1 and 4 pounds of actual nitrogen per 1,000 sq. ft. per year is considered adequate for tree growth and development. Never apply more that 11/2 to 2 pounds of nitrogen per 1,000 square feet in an application.
• Mulching reduces the need for close mowing and trimming, which will help prevent mechanical damage by lawn mowers, string trimmers and other mechanical equipment. No more than 2-4 inches of mulch should be in place at any one time. Don't allow mulch to build up, as this can cause serious problems, such as cankering, girdling roots and reduced oxygen.
• Prevent damage to tree trunks and root systems by the indiscriminate raising or lowering of grade during construction. Grade changes around trees may result in death of the tree, although symptoms may not appear for 3 to 5 years or longer. Putting a raised bed around the trunk of a tree can also result in long-term damage. Rototilling beds under trees is another common way of damaging or killing trees. Shrubs and annuals under trees should be pocket planted.
• Watering is important. Under normal circumstances in Ohio, 1 inch of water per week during the growing season is adequate. Many trees will require water during the establishment period, but once established are tolerant enough to survive most droughts without supplemental irrigation. However, inadequate watering during drought periods can result in increased sensitivity to insect attack, which will often show up 2 or 3 years after the drought stress was present.
• Prevent soil compaction around mature trees. The best way to alleviate compaction is through a technique called vertical mulching. Holes are drilled 2 feet on center about 18 inches into the soil and 2 inches in diameter. Care is taken to ensure that major roots are not damaged. These holes are then filled with organic or inorganic matter that allows oxygen penetration into the soil. Vertical mulching without fertilization may result in a better plant response than fertilization alone in some circumstances.
• Pruning is important during a tree's entire life. Where branches join at angles less than 35 degrees, one of the branches should be removed. Weak, damaged and diseased branches should also be removed, as should branches that are too low to the ground. The first structural branches for a tree should be at least 7 feet above the ground. If you know a branch will require removal later, keep it pruned back so that it does not become a major part of the tree canopy.
• Cabling and bracing can be used to make a plant more structurally stable. This type of work should be done only by a professional. Once cable and braces are placed in a tree, they must be inspected every 3-5 years to ensure that they remain effective. The tree becomes dependent on the braces, and if the cable or brace fails, the tree will be more vulnerable to damage than if it had not been supported. In urban areas, the standard of care required for plants is higher than would be required in forested areas. There is a duty on the part of the resident to inspect the trees on a regular basis. Where safety is questioned, contact a professional.

Further Information

A number of sources of information are available to you. Your local utility company frequently employs utility arborists who can help, upon request, if the tree is near a utility line. The Ohio Department of Natural Resources, State Urban Forestry program, and county offices of Ohio State University Extension also provide advice. Contact a professional arborist when tree work is required. Arborist firms should be investigated to ensure that they have adequate insurance to protect you and adjacent property owners in case of an accident.