Tree Care During a Landscape Conversion

Not all trees are worth protecting during a landscape conversion. If you answer "yes" to the following questions, the tree is worth saving.

• Is the tree healthy?
• Is it healthy enough to survive the stress the construction will cause?
• Will the tree be able to adapt to the new environment?
• Is the tree compatible with the new landscape?
• Does the tree fit the design?
• Is the water-use of the tree compatible with the plants that will be installed around it?
• Is it providing valuable shade?

Protecting the tree

Even with careful planning, a tree's root system is often disturbed during a landscape conversion or other construction project. Roots left behind lose the temperature buffer and water source provided by the lawn and the sprinkler system, which leads to drying and additional root loss.

Convert during the cool season
You need to water deeply several times in the weeks prior to starting the project, so plan for a cooler time of year such as fall or early spring. Leaves lose less moisture in cool temperatures, reducing the amount of water needed.

Identify and protect major roots
Examine the area around the tree and try to identify the roots that are close to the surface. Note their location and keep damage to an absolute minimum.

Grass removal
When removing grass around trees, use herbicides and a dethatcher instead of tractors or other equipment. Heavy machines can crush existing tree roots, break branches and wound bark tissue.

Protection zones
If you plan to use a tractor, sod cutter or other heavy equipment, erect a protective barrier around the tree at the edge of the canopy. This will help keep renovation equipment at a safe distance from the tree and avoid physical injury to the trunk and branches. Keeping the equipment away from the tree also will reduce damage to the large woody roots and reduce soil compaction. If you must use heavy equipment near the tree, use plywood where possible to spread the weight of the machine over a larger surface to reduce soil compaction.

Trenching under the canopy
Avoid making any trenches under the canopy of the tree to minimize cutting the roots. Remove any damaged roots, making a clean cut to help the root heal and regenerate. Consider tunneling under roots instead of trenching.

Irrigation replacement
In lawn conversions, sprinkler systems are typically replaced with drip systems. When installing the new irrigation system, you must supply water where it will be needed--under the canopy and out to the drip line.

Weed barriers
Don't use plastic sheeting under rock or organic mulches. Water and oxygen cannot penetrate the soil. If a barrier is necessary, use landscape fabrics, also known as geotextiles or weed blocks. These products allow water and oxygen to penetrate the soil and reduce weed growth.

Mulch
Install mulch correctly. If it's too shallow, you won't receive the benefits of the mulch. If the mulch is too deep, you can cause harm to trees and plants. Deep layers of mulch work well to suppress weeds, but can lead to excess moisture in the root zone, which can stress the tree and cause root rot. Piling mulch against the trunk or stems of plants can lead to insect and disease problems. Keep the mulch 2 to 4 inches thick. Taper mulch away from the base of the tree for the best results.