Around this neck of the woods everyone does it in the spring. Nobody has ever done aerating in the fall here ever. I do my own yard 2 or 3 times a year and its better than any of my customers yards. I get about 2 more mows out of mine than my customers as well. As far as the dethatching you obviously are a rookie. Thats supposed to be done when its dormant. Your response doesn't impress me much there pal.Lol, thats gotta be a joke whipples. 3 aerations a year? Haha. Best time for aeration is fall time, dethatching can be done anytime you feel like making a mess and tearing up your yard.