I am using CGM as pre-emergent for the first time this Spring. Should I water after spreading or just let nature take its course? This is a big step for me. I have always had good luck carefully using chemicals. Now I am paying more than double for stuff that is proven to be less effective. I feel better about it, but I sure better not have a mess of crabgrass this summer, or my tree hugger leanings will disappear.