Corn gluten meal has some interestingly promised characteristics for the prevention of weed growth. However, it is a bit pricey if it doesn't really meet expectations!.
For those who don't know - corn gluten meal is the by product of ethanol production;ie, the leftovers from the corn kernels used to make alcohol. It can be purchased in small bags of 20lb for around $30 locally. In one form, it comes as small dry yellow grains about 1/16" diameter or as a powder. It is also available at the ethanol plants in a wet mash form - typically used for cattle feed. The dry package claims it should be spread about 20 lbs per 1,000 sq. ft. But this is mainly for lawn weed control. It supposedly works by preventing the seeds from germinating so you obviously don't want to apply it until the seeds you have planted have come up. It also purports to supply nitrogen for the growing things
If effective as claimed it should work great for gardening weed control (the dried, bagged stuff). Haven't found any claims for the fresh wet stuff but that would probably be cheaper to purchase!
If it works as claimed, it could be a great gardening aid!!!!
No mention of what other chemicals may still be left in the gluten from the processing. Has anyone heard anything about that? Could be a problem for vegetables!!!!
It apparantly won't have any effect on a lot of the grasses as they probably already have their roots established (with dormant tops) or spread by rhizomes. It should limit those annual grasses spread by seed from the previous year.
So if anyone has tested any of this stuff, please add a few lines on your results!
I have not used it, but it is recommended by organic folks, so I think "chemicals" probably aren't an issue. I have heard some question its effectiveness. Here's a link to a few corn gluten discussions (alphabetical listing, scroll down): http://www.gardensalive.com/article.asp?ai=492.
If it is Preen, then I have used it; I believe it worked fairly well. Most of those weed preventers I have read work by preventing seed germination. You have to be careful where you use it - can't seed for 2 weeks after application. It doesn't work on existing weeds, but since weeds seeds turn up everywhere, I thought - it give it a try. A gardening friend had recommended it. I used it early in the season when applying food and turning some soil prior to any planting, and it did lessen my weeding chores.
I've used corn gluten successfully. I raked it in the area before transplanting onion starts and also scattered it around tomato transplants. It doesn't completely inhibit all weeds, but greatly reduced the amount of weed sprouts. It doesn't work on existing weeds or grass. I don't know how well it works with grass seeds.
How expensive is corn meal? Just a thought. I talked to a guy that said he used chick scratch and he claimed it was just as good as preen. What he never said was how many mice and rats he fed lol. I use a hoe ,and a tiller, and a1920 high wheel weeder or cultivator, and black plastic.
I buy my preen at season-end sales of 50% off... still not cheap. Cornmeal has other components besides gluten, so not as noticeable effect. I would agree that my wheel hoe and scuffle hoe do a very effective job.
I didn't have much success but in retrospect, I think I should have watered it in well.
I have heard that the effect is cumulative, that it works better if used for several years.
The kind I used was a corn gluten meal organic lawn fertilizer that did NOT claim to be a pre- emergent. It wasn't too expensive.