There are a couple of downsides to using corn gluten. One is that timing is everything. If you are using it as a pre-emergent weed control, you've got to use it BEFORE weeds appear in your lawn or garden. Once the weeds come up, the corn gluten won't do much for you. The key is to stop the weed growth before it starts, which is what the gluten will do for you. You can also use it if you have weeded the yard well, then put down the gluten. It worked for me last year doing it that way.
The other downside is...well....let me share a story with you. I had a couple of bags of corn gluten in my shed in the backyard. One bag was on the floor, the other on a shelf. I hadn't been in the shed for quite a while being that we had just gone thru winter. Now that it was spring (last year), it was time to get in the shed, get the tools and get busy. And guess what I found when I opened the shed door? There was corn gluten everywhere! All over the floor, in a pile in the corner and all over the shelf. Seems the little mice that frequent our yard found a way into the shed and discovered the corn gluten. That's right....they feasted for apparently the whole winter! Little piglets munched quite a bit after tearing open the bags and believe me when I say they left a nasty, stinky mess in my shed! Moral if the story....if you're going to use corn gluten, store it in something the mice can't get into! I now have mine in a closed plastic bucket, safe and sound.
Anyway...corn gluten is a good product to use before your weeds start to sprout. It will really help to keep those nasty buggers at bay! (the weeds, not the mice!)
I'm looking forward to a beautiful sunshiney weekend so that after I get my taxes done Saturday I can spend the day playing in the dirt. Ok, it's still mud, but I can still play in it!