What are your opinions on when to put down pre-emergent? I'm in Kansas City, MO & we have extreme weather changes from day to day. It has been 70* one day & 0* w/ 8" of snow on the ground the next. They are calling for upper 50's this week, but will probably drop down again next week. I am just trying to decide when would be the best time to start. It seems like the last couple of years I have been a little late on my apps. Thanks for your help!