Can you over-apply corn gluten meal as a weed supressant?

May 23, 2009

Hi, I'm new here. Not sure where to post this... it's actually probably an "organic landscaping" question, but there is no forum for that I can see. I also x-posted this in organic lawn care.

I decided to replace a large area of lawn around my home with landscaping. It's a sloping hill off the side of my house and was really hard to mow anyway. It's about 1,000 square feet. I planted in lots of native spring ephemerals and native bushes, surrounded by hardwood mulch.

The trouble is, I have silver maple trees along the driveway right next to this area. They drop thousands of propellers in spring, and I found that keeping the area weed and maple seedling-free was nearly impossible by hand.

So I followed the advice posted in another thread on this site, and I went to the feed store to get Corn Gluten Meal as a pre-emergent for weeds. I got a 50 pound bag for just $22. Apparently this product is marketed as Organic Preen and under other brand labels, but it's much more expensive than buying the raw stuff from the feed store. Long story-- Iowa State University accidentally discovered CGM's weed suppressant abilities, and now they license it. Meaning they collect money from products like Organic Preen. Anyway.

So I applied CGM to the area before re-mulching with hardwood bark. I could not tell what setting to put my spreader on. Everyone says it's 20 pounds per 1,000 square feet. I ended up putting the entire 50 pound bag down on my 1,000 square foot area.

Now, the area smells. Really bad. Like something fermenting or rotting or both. Could I have done major damage? Why would it smell that bad? I've done numerous web searches and found nothing. I'm sure the smell is from the CGM. I just hope a bad smell is the only negative... could I be ruining the soil or hurting the plants with this over-application? I wish I had been more careful, but this is what happens when you are working with a product from the feed store that has no label on it to help you know how to spread it.

I guess what I'm trying to say is, please don't berate me for making a dumb mistake... that much I know. If you have helpful info on what I can do to correct any potential problems that might arise, that would be good. I'm also just really curious where the smell is coming from. Does corn ferment when there is too much of it?

Thanks for your thoughts.

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