Department of Parks and Recreation
Tree Care Tips
Tree Care Tips
Many of Arlington’s trees are on private property in residential neighborhoods. When a mature tree is lost, young trees may require fifty years or more to fully replace it. Trees are valuable assets, and giving them proper care is a good investment. Here are some tips for taking care of mature trees:
Mulching. Organic mulch should be applied over the tree roots. Mulch should be applied 2-4 inches deep and cover as much of the root system as possible. The roots extend beyond the crown of the tree, but mulching the entire area under the crown should be adequate in most cases. It is better to have mulch instead of grass above tree roots because organic mulch enriches the soil while grass competes with the tree for water and nutrients. Mulch should be kept a few inches away from the trunk and never piled up around the trunk (often called “volcano” mulching).
Watering. In dry periods, even mature trees need to be watered. To be fully effective, water should penetrate the top 12-18 inches of soil, where most of the roots are located. A thorough soaking once a week is much better than frequent but light applications of water.
Invasive Plants. It is very important to keep English ivy and other invasive plants away from trees. Trees covered by English ivy are weakened and eventually die as the ivy spreads over the crowns. Even if invasive vines are kept off the trunk of a tree, their presence above the roots can damage its health. Like grass, invasive plants compete with trees for water and nutrients.
Pruning. Trees need their branches and leaves, and they should be pruned only for good reason. When mature trees require pruning, most residents will need to hire a tree care firm to do the work. Tree care firms should employ certified arborists to plan and supervise the work. Responsible tree crews use ropes to lift themselves up into a tree; they never use spikes to climb living trees.
Topping. Topping means cutting off large numbers of branches and leaving the stubs. It is an extreme form of pruning that severely damages trees, making them vulnerable to insects and disease. Trees should not be topped, and tree care firms that suggest topping trees should be avoided! When it is necessary to limit the height or spread of a tree because it is close to buildings or utility lines, there are alternatives to topping. This is a situation where homeowners should engage an ISA (International Society of Arboriculture) Certified Arborist or a Consulting Arborist (American Society of Consulting Arborists).
Consulting Arborists. As noted above, there are situations where homeowners need the advice of a Consulting Arborist. Usually the only service Consulting Arborists offer is advice and so they can be entirely objective about recommending pruning or other tree maintenance work. Examples of situations that warrant the services of a Consulting Arborist are: some branches appear to be dying back, fungus growth on the base or trunk of a tree, planned construction activities which will encroach into the root zones of trees, and excavation for utility lines which may damage tree roots. Consulting Arborists should also recommend competent tree care companies to carry out needed work. A list of ISA Certified Arborists can be found at www.goodtreecare.com. Consulting arborists can be found at www.asca-consultants.org.