I have two medium-sized shade trees located in my backyard planting beds that have died this spring and need to be removed. What do I need to consider before having the trees removed?
— Jennifer Garrett, Crystal Lake
If the dead trees do not pose any safety hazards, consider waiting until winter or late fall to remove them to lessen the impact on your garden. Consult an arborist if you are unsure whether the trees pose a hazard, but I think it is unlikely since they just died this spring. You may be able to secure better pricing if the work is done in the winter. The branches that fall on the garden and the crew walking around to remove the trees will knock down perennials if the removals are done during the growing season. Most will probably be fine next year, but this would spoil the appearance of part of the garden for the remainder of the gardening season.
Shrubs, ground covers and perennials within a foot or so of the stumps will likely be destroyed or damaged when they are ground out, so you may want to temporarily relocate them before the work is done. If the stump is 2 feet or more in diameter, clear a space that is 2- to 3-feet away from the stump. Your contractor can advise you on the amount of space they need to grind the stumps. Have the stump ground to be at least 12 inches deep if you want to plant new perennials in the same location. The more soil depth you have, the better it will be for growing perennials. New trees and shrubs with a large root ball will probably need to be planted adjacent to the old stump. Expect to cut through old roots from the tree while planting. A sharp ax works well for cutting out larger roots.
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The stump-grinding process will leave a mound of chips mixed with soil that will need to be removed and replaced with topsoil. Be sure to remove the wood chip and soil mix down to the bottom of the hole left by the grinding process. If you plan to have the stumps ground out this winter, you should transplant any valuable perennials and shrubs that are next to the trunk of the tree this fall in preparation for the removal of the tree stumps this winter. The stump grindings can be piled up in the back corner of the yard to decompose over a couple of years, leaving you with topsoil to reuse in your garden. The loss of a large shade tree will increase the amount of sun for your garden, which can affect the performance of existing plants. If there are other adjacent trees that provide shade for the beds, the impact will be less. It is a good idea to plan ahead to determine the need to relocate plants that may end up being in too much sun next year and replace with more sun-loving plants. Trees and shrubs in gardens grow over time and gradually increase shade. As light decreases over time, some plants can start to struggle and when a tree is removed, the light levels return to more optimum levels for the plants. If you are unsure of the impact the tree removal will have, observe how the plants respond to this change in your garden over the growing season and adjust their locations if you see problems with too much sun.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.