Once you've watered them in, the open areas shouldn't be a problem since they work underground. We apply in early early spring, mid/late spring, early fall, and then late fall (mid-Oct) when we do the 4 times a year. The past couple of years, we've only needed to apply twice a year and we do it in early, early spring to catch cutworms, grubs, and other pests, then in mid-late fall.
