Hello Sandy, It is hard to say the exact date when dropping of acorns will stop. Most of them drop in early to mid fall, but members of the red oak group (such as pin oak) tend to be a little later than those in the white oak group. For example, now (September 28) in southern Illinois white oaks are starting to fall in earnest but many of the reds oaks are not dropping many acorns yet. I would say that usually by late fall (December) most of the acorns will have dropped but some may continue to drop throughout the remainder of fall and into early winter.
