I am not sure about pre-emergent and seeding. I have used Baryer Advanced on my chickweed...after three applications--five to seven days apart...most of it is dying. Darn stuff is hard to get rid of. I was going to try the Ortho...but had a big new bottle of Bayer left over from last year.

I want to research the pre-emergent and seeding issue...as I am in the same situation. I do not want to deal with chickweed again next spring.

From what I've heard, even if you are using pre-emergents which are "safe" to use with seeds, like Tupersan (Siduron), you are using less than what is necessary to stop the weed seeds from germinating and risk the chance of your grass being deformed by the pre-emergent. So I've decided not to mix the two.

For the Chickweed, I recently pulled as much as possible by hand and mowed as much of the heads off as possible. Then I seeded. I plan to spray the chickweed with Ortho Chickweed killer after 3 mowing of the new grass. Then I will seed again in late august. Once the fall grass seeds have sprung, I will apply a preemergent (this should be late fall/early winter). I will apply another preemerget in early Spring and hand pull/spray any remaining chickweed if it emerges into the summer. By then I think I can get onto the regular pre-emergent in spring and overseeding in fall routine.

The only things I need to decide on is whether or not to use CGM or a chemical pre-emergent. I'd much rather go organic, but I need to see some serious data showing that CGM works well. I also need to find out if applying a preemergent in the late fall/early winter is too late for the fall germinating chickweed seeds, and whether or not this will affect my seeding in the spring.

Hope that helps.

I had the same problem this spring after establishing a new lawn following a septic system replacement.

I pretty much have it under control now, but like you, I don't want to see it ever again!

What chickweed pre-emergents are available? What is CMG? I live near a lake and don't want to contaminate the environment more than I need to.

Thanks.

CGM is corn gluten meal (I get confused as to whether its CMG or CGM). From what I know, there is a difference between corn meal, which can be used a an organic fertilizer to provide protein to your soil microbes who in turn provide the necessary nutrients to your lawn, and CGM, which acts as a natural pre-emergent and mildicide.

I talked to someone who was very knowledgeable at a lawn supply distribution center (they sell to golf courses) and who sells CMG. He told me that CGM is very selective about the weeds and mildews that it controls and needs to be applied at just the right time of year and in just the right moisture environment in order to work at all. This is a guy who discouraged me from using chemical mildecides because of harm to the environmental, so I don't think he is against organic methods. I just think that he doesn't think CGM works very well in a lot of cases. I tried it once and I had weeds a plenty that season.

I wish I knew which chemical pre-emergent was safest (for my kids). I hear that Tupersan (Siduron) is relatively safe, but that is because it is usually applied at very low levels in order to be useable with new grass seed (it's claim to fame). The lawn guy told me that once you bump up the rate to an affective level, it becomes just as toxic to the environment as the other chemicals solutions.

If you get any info on this, please let me know.