On beds of permanent plants, trees, hedges, and grass, an annual top dressing of compost can help maintain the health of your soil and landscape.
We recommend applying a 1/4″ deep layer of compost (NOT fertilizer; there is a difference; fertilizing trees when they are in distress can actually cause more harm than good) to the entire critical root zone (CRZ) of each tree you are concerned about. Organic compost can be purchased from any gardening or landscape supply store (i.e. Whittlesey (screened organic cow manure compost), Lowes, etc.). Do this between October and Mid-May as any later and you risk the compost burning the underlying vegetation due to sun exposure and high temperatures.
If your soil is compacted then the OUTER 1/2 CRZ should be vertically composted (augered or air spaded holes filled with compost and backfilled).
Here is an article on how to calculate and properly apply a top dressing to the CRZ: http://www.treesquad.com/blog/2016/4/28/how-to-properly-treat-and-protect-your-trees-critical-root-zone
Within 24/48 hours of fresh compost being applied, a good soaking watering should be performed. Good soaking watering = ground damp 4-5″ deep (oscillating sprinkler, 30-45 minutes; sprinkler system, 20 minutes; can take up to 2 hours depending on watering method and soil composition).
