When to apply pre-emergent this spring?
There are general guidelines on when to apply crabgrass pre-emergent that are, indeed, thrown off by our wacky weather. So, the fall back is to rely on what the plants tell us. The rule of thumb based on nature's timing is to apply it when the forsythia blooms drop off.
See our crabgrass pub: TT 43 (link is external) - Herbicides for Crabgrass and Goosegrass Control in Turf