When is the best time of year to put down pre-emergent crabgrass preventer ?? Should I consider a post- emergent application??? What do you think of milorganite 3-4 times per year vs a fertilizer of 10-10-0???
The best time of year to put down crabgrass pre-emergent is to do a split application, the first during the blooming of the yellow forsythia shrubs, and then again 4 to 6 weeks later.
A post-emergent is generally only used as a backup, so concentrate on the pre-emergent. Try to find one that only contains the pre-emergent, not also a Nitrogen fertilizer (though you will find many and hear lots of marketing/ads suggesting this- "weed and feed").
See our Crabgrass page here for more information: http://extension.umd.edu/hgic/topics/crabgrass
Regarding fertilizer, due to Maryland Turfgrass law make to protect the Chesapeake Bay, you should not be able to find a 10-10-0 fertilizer. The middle number, standing for Phosphorus should be 0.
Our best management tips, such as mowing high and leaving the clippings,(provides the equivalent of a fertilization and is free versus Melorganite) can be found within our lawn page here:
Any other fertilization is best left until fall.