Question
What is the correct procedure for using Corn Gluten Meal Organic Weedkiller in the spring?  I read that you said to put it on when the forsythia starts to bloom.  But there was also something about it needing to be dry. Can you please explain the right way and the wrong way?

Answer
"Greenhouse Screening of Corn Gluten Meal as a Natural Control Product for Broadleaf and Grass Weeds" (http://www.gluten.iastate.edu/pdf/grnhsechr.pdf) was a test conducted in 1995 at Iowa State University of how well Corn Gluten Meal keeps 22 weeds from sprouting.

Best results were seen against Black Nightshade, Common Lambsquarters, Creeping Bentgrass, Curly Dock, Purslane, and Redroot Pigweed.  Dandelions, Catchweed Bedspraw, Giant Foxtail, and Smooth Crabgrass fared slightly better.

Velvetleaf and Barnyard Grass were toughest.

Researchers observed: "The efficacy of CGM for control of a particular weed ... depends on the amount of CGM applied.  Broadleaf species were generally more susceptible to CGM than grasses ..."

But as you point out, there is a RIGHT way to apply this weedkiller and a WRONG way.

To do it RIGHT, you can watch for the yellow Forsythia bloom in your area.  But Weeds sprout when soil temperatures reach around 55 degrees F.  There is no compromise here.  You must get these weeds at germination, or the CGM will not work.

You need a time that it will not rain for several days straight.  Apply the CGM; water it in; let it dry out.

In the days that follow, weed seeds will begin germinating.  The CGM will stop root and shoot growth.  Goodbye, Weeds.

DO NOT apply if the Weatherman says, "It Looks LIke Rain."

Yes, I know, this is hard to do.  Especially in April.  Remember that old saying about April Showers?  That's what makes this hard.

It may rain a lot.  Or a little.

You want NO rain at the right time, for 3 days straight, minimum.

Of course it goes without saying that you cannot sow a new lawn at the same time.  You must wait at least 5-6 weeks before sowing any more seeds.  Longer is even better.  Just to be safe.

Anything that has already germinated and is growing roots will probably survive your CGM assault.  Be ready to get this stuff down when you need it.  Strike while the iron is hot.

Any questions?