My experience is that it does a pretty good job, but not a total job of inhibiting weeds. After a second application, a couple of months later, it was more inhibiting (maybe the cumulative effects?). However, I was impressed at how good it was at greening everything up. Worked well as a fertilizer, but too expensive to use solely as that.

Idabean, could it be that you need to give it a little longer? Most organic remedies need time to work. Keep noticing the areas and see if the sprouting doesn't really slow down, and pick the existing weeds in the meantime.

Anna

I've had good results with CGM as well. I love to use it in permanent beds, particularly strawberries. Like you, I found that the commercial kinds of CGM were expensive. When I needed more, I went to my feed dealer who could order 50# for $14. This has been a couple of years ago so the price is probably different (higher?) now. Just be sure you ask for yellow CGM.

Corn Gluten Meal sold for weed suppression must pay Iowa State University royalties so the stuff sold as "just as good as" but without the royalties attached may not be what you think it is, and if it really was not Corn Gluten Meal then it will not be nearly as effective. All corn meal products will have a fairly high ratio of Nitrogen to Carbon and could make a good addition to the compost pile.

The stuff I bought was that silly rooster name, and for what I paid for it it better be the real thing. I'll let the areas I can manage go, and reapply later, but will have to take different measures on a hillside reclamation project that is difficult to work on.

Thanks for your observations.
Marie

The effectiveness of CGM as weed control also has to do with the timing of its application. It doesn't inhibit seed germination but rather prevents root development. You need to time the applications to when weed seeds are most likely to germinate in your area. Too early and it may lose effectivness before it can do its job and if too late, root development could be too far advanced for it to have impact. Most weeds produce seeds that germinate in spring and fall but specific times will vary with region and with the species.

You may be better off using a true pre-emergent herbicide that prevents seed germination, especially in areas that are difficult to access or if timing is a concern.

gardengal: would Preen fall into that category?

Timing is very important as was said above. Also, there is a corn gluten feed that is different from corn glutem meal. But to answer your question, it is 9% nitrogen and can be used as a nitrogen fertilizer.

this is the CockaDoodle Do stuff advertised as an inhibitor to weed germination. So, what might a schedule of application look like? If it can be effective, perhaps I can use it to greatly reduce the use other chemicals, even if not all. I mean I understand what was said about getting it down before germination...but paint the picture in more detail for me, please!
Marie

In my 2-year trial experience, I found it is not a particularly good fertilizer and it is not effective in suppressing weeds. In that 2 year period I saw no effect on germination or growth. Beginning in early spring, I kept a layer of it in sidewalk cracks, between pavers, and in a small vegetable garden. A layer of bright yellow meal was always visible, all spring, summer and fall. The weeds grew very well thru it.

I suppose the elevator could have sold me something besides corn gluten meal, but I don't know why they would.

Bean counter--what kind of weeds were growing through it? It doesn't block weeds from growing, just from germinating. So if you had problems with perennial weeds already there, the CGM wouldn't help.

bp, I agree that perennial weeds would not be affected. However the dandelion, sweet annie, cleome, ragweed, various tree seedlings and morning glory shouldn't have kept sprouting thru out the summer. That's my experience. I don't know how our dry summers effect the cgm or if there are other factors. Believe me, I really wanted this to be at least partially effective. Suggestions welcome.

CGM should be spread in early spring. The rule of thumb is when the daffodils and forsythia are blooming. Ideally it should be watered in well followed by a long dry period. Under the best circumstances it can cut weed germination by a little over 60% the first season. After a few years it can be as much as 90% effective. A supplemental fall application will also increase effectiveness.

I read that it should be spread just after the second time you mow your lawn, and also that it should be spread when the forsythia bloom (but when? Just as they bud? Just as they drop? Be specific, people!) and these two things are not compatible.

I've had good results with it in the veggie garden when I spread it, um, around that second-mowing benchmark. I never felt that it worked well in the lawn though, I guess I timed it wrong. But it works fine as a fertilizer.

I have had good success with it on my lawn. I haven't used it anywhere else. I apply it around the 15th of April (April 25 is our average last frost date)which is before my first mowing, but it could be even earlier if things warm up quickly. Phenologically speaking, I guess its about the time procrastinators file their taxes ;-).

tj

spring weed germination is triggered by soil temp, usually in the high 60F's. one strategy would be to first apply cgm when soil temp reaches 66F so it would be in place during weed germination at 68F soil temp a few days later. that is what I tought for my zone.