I Have A Shaded Back Yard With A Large Section…
Gary Asked
I have a shaded back yard with a large section of dwarf mondo grass. I also have an elm tree that contributes not only shade but thousands of elm seedlings. Is there a pre-emergent that can prevent this? The manual method of removal is just too exhausting and trying to cut with a trimmer, and also cuts the mondo grass (and I am not sure it is that effective). If there is a pre-emergent, is it best applied in the fall or the spring or both?
The Gardener’s Answer
Hello, Gary: There are foliar pre-emergent sprays that are not recommended by most certified arborists because of the potential damage it can cause to the long-term health of the tree. That said, it certainly is not practical to mow down the mondo grass every time an elm seedling pops up. The mondo grass would prefer that you do not do this and mowing will not get rid of the seedling roots. These trees can be high-maintenance because they are messy and hand pulling is still the best method of control, but there are pre-emergents that will help prevent the fallen fruit from producing seedling growth. Preen is a very common pre-emergent found in most garden centers. If applied at the proper time it can be effective but it will need to be reapplied according to product label. Corn gluten meal is an organic alternative to Preen and other chemically derived pre-emergents. It works in the same manner as it prevents seeds from germinating and forming roots. Both the chemical and organic products will need to be reapplied every four to six weeks depending on product. Either way, timing is essential to being successful. You can start applying a pre-emergent in the early spring and continue to do so throughout the growing season. Be sure to water it in well, especially if the mondo grass is really dense. You want the product to be absorbed into the soil and if left dry it will not be effective. Refer to label for application rates. Do not get too discouraged if you see a few seedlings pop up after the initial application; it will take several applications to get the seedlings under control.
