The research done on using Corn Gluten Meal for "weed" suppression says that 80 pounds per 1,000 square feet is the minimum to be effective, or 1200 pounds of CGM to adequately cover 15,000 square feet, for "weed" suppression.

I'm in your area and cut my grass twice already. It really does look better, but I have a small yard. I'm not sure it's worth the expense on big yards. I think if I had bigger I'd do something else. Also, because of warm nights since January, some dandelions and those white flowered things beat me to the punch, and I put it down 2-4 weeks earlier than normal.

Every study I have read says 20 lbs per 1,000 sq. ft. is sufficient for weed suppression.

http://www.extension.umn.edu/yardandgarden/ygbriefs/h531cornglutenmeal.html

I applied 20 pounds per 1,000 square feet every month of the growing season in 2011. Starting in March that was 8 applications or 160 pounds per 1,000. I saw absolutely no suppression of new weeds.

If that happened to me, I wouldn't use it again. But so far, I like what I see.

That seems to be a common denominator with regards to success using CGM- some people have success, some people don't. I am one that had major success two years ago, but only mediocre success this year (the warm temps came early). I wish there was a way to scientifically test out different grass/dirt setups with this stuff to see if it's something with the grass/dirt/organic/non-organic/cgm combo that is either working or not working. Does timing in fact have an impact on success? Does application rate apply....especially when referenced to the previous mentioned testing ideas?

Until those questions are answered, I refer to CGM as (C)ould (M)ake (G)row.

Or, C.ould G.row M.ore

This was the first time I tried CGM. I got it down about a week before the forsythia bloomed cause stuff was already greening up. As far as I can tell, it did nothing for the weeds, but now I am spending all my free time cutting the grass as it is growing like crazy!