The soil test I had done this past February (2017) indicated that I should fertilize my lawn this fall, once between Aug. 15 and October 1, and again October 1 through November 15. The fertilizer recommended is 26 -- 0 -- 3, or the equivalent. We also have quite a few shade trees in the lawn area, and I want to know if this lawn fertilization program will be adequate for the trees as well, or if I should also fertilize the trees. If I fertilize the trees, too, what should I use, and should I then adjust the lawn fertilization so that I do not fertilizer the lawn within the drip line of the trees.
Prince George's County Maryland
Mature trees do not need to be fertilized, but when you fertilize your lawn some of the fertilizer will inevitably move past the grass roots to the tree roots. This is fine.
We do recommend that you grass-cycle, i.e. not collect grass clippings but rather let them lie and slowly decompose, feeding the grass and roots below. Also, in the fall, if you can mow fallen leaves (until the leaf cover becomes too deep), these bits of leaves also decompose and feed the trees--the natural food of trees in the wild.