I've used it and had some benefit (I think, no control area). In our climate it needs to be applied twice a year (at the correct time) and for 2-3 years to get the most benefit. If you google education sites I'm sure you'll find lots of more detailed info. Best wishes...

Here is a link that might be useful: extension websites with info on corn gluten

I have also used the corn gluten. One thing to remember though regarding the organic bit - most corn is genetically modified and just because this is a bi product of that does not make it certifiable organic (if that is of importance to you). From my recollection it did work, but being yellow, caused a yellow 'stain' on the mulch for several days. I also recall an odor from it.

I've not used it, but it comes up in the Lawn Care forum quite a bit. It is used as a pre-emergent herbicide for annual weeds, and can also help to fertilize the lawn.

The University of California did tests on it and I was told concluded that it was a good way to dispose of corn waste, but was not effective.

Penny

I wonder what the variables are that caused differing results. Several other Extension services found value in using it as a weed suppressant. It would be nice if "the experts" could tell us what makes it effective sometimes and not others.

The variables include amount of rainfall or irrigation after application, the weed species being controlled, area of the country, application rate, the time of year and others. It works best where once applied and watered in, little rainfall follows. Too much water will allow the affected seedlings to grow past the effects. This also means the effectiveness depends on the area of the country and its climate. It should also be understood that the herbicidal effects last 4-6 weeks, at best. This is one reason it is often used as a crabrass preemergent since the germination window is relatively short. It also acts as a fertlizer and some conjecture that a good measure of its weed control in lawns comes from the CGM fertilizing the grass so it crowds out competing weeds.

I was not aware that CGM is prevented from being OMRI approved. The link is to an OMRI listed CGM product.

Here is a link that might be useful: CGM label

I was not aware that CGM is prevented from being OMRI approved. The link is to an OMRI listed CGM product.

In theory CGM is fine and fulfills the OMRI in that indicated section. BUT..... somewhere else in the document (I don't have it at hand) there is a section that requires you know the source of the material. This is where the muddy line gets drawn. For my certification I was warned not to use CGM as we were in an area where the Monsanto signs outnumbered the realtor signs!
And Organic certification to some is more than just going by the written rules, it is about a way of growing that is sustainable etc. etc. so whether it is in the government document or not, it is suspect by some regional certification inspectors.

I use it and recommend it. The only problem I've had is that the local mallards and geese like it too although after one good rain that ceases to be a problem. In my area we do have to apply pre-emergent twice a year but the CGM works great whenever I've applied it.

I have had some water soluble Peters fertilizer for some time. how long would it remain good? do the chemicals in it become ineffective in time?

Hey Napapen,
Do you have any reference for that study you cited? Thanks.

When asked about it as a weed suppressor in a California native garden, I finally found a reference saying it provides too much nitrogen for native plants.

Iowa state has done quite a bit of research on CGM. My impression is that it can be effective, but may not work as quickly as traditional synthetic pre-emergents. The main problem with it that I see is that it is not readily available locally, and when you find it online, it can be pricey to buy and ship. This may not be the case in all areas of the country.

Here is a link that might be useful: Iowa State info on CGM

What price is our environment worth? hard to replace it once it's gone...