I've read that CGM should be applied when average soil temperature is between 52F and 58F. Many people apply CGM when the forsythias bloom.

-Deerslayer

Thanks. It will be easier to check soil temps rather than the forsythia bloom. We don't have a really hardy variety here and often the late freezes get the buds.
S.

The way it works as a preemergent is it inhibits the growth of seed's tiny feeder roots by causing a break down in the cell wall. The seedlings struggle to get enough moisture, which causes them to die before they ever have a change to take hold.
When used as a preemergent CGM should be applied in the 4-6 week time period before target-weed germination. In most case this is once in early to mid-spring and another in early to mid-August.

Deerslayer's right about doing it when the forsythias bloom.

-Todd

You can check your local soil temp reading...usually there is a link on Univ. AG pages...apply when it is 50 degree F. Seeds begin to germinate when the soil temp reaches this temp...

According to Cornell University:

"In a dense stand of turf under a medium maintenance program it was found that soil temperatures greater than 73° F. were required for significant crabgrass seed emergence. It has also been reported that minimum temperatures of 55° to 58° F. at daybreak in the upper inch of soil for 4-5 days will encourage the initiation of crabgrass germination. Other research has shown that mean soil temperatures of 62° to 65° F. are required for germination."

Here's a link:

Crabgrass Germination

I am assuming that crabgrass is your primary target for your spring CGM application.

-Deerslayer

Here's what an organic lawn product supplier has to say:

"CGM must be applied before any germination takes place, usually prior to the soil temperature reaching 60 F."

Here's a link:

CGM Fact Sheet

Ntbio, please do some research before confusing people by disagreeing with earlier posts.

-Deerslayer

deerslayer...you have pointed to a report fopr Suffolk cty that is out of date as it mentions the use of a now EPA discontinuted product called MSMA. You are proving you can google and read two lines and think you are an expert...you are not even giving decent or pertenent info...please stop...stick with salt licks on your front yard for your deer since you don't supply the correct fertilizers for the deer to prefer your grass becaus eof improper soil nutrition...

Placing CGM at soil temp 50 degrees F as shown by the local university AG soil temp page will bracket the accptable algorithm for soil temp increase and provide the best change that spring seed germination will be suppressed. Most likely the air temps during this time will be a matter for your zone...ask your cty extention office or the local UNiversity for a hand...we;ve had temps in the 60's already here in GA but the soil temp is only 45 F because the night temps are still in the 20-30's.

The efficacy will be about 6 weeks before the material breaks down to simple N by micropial activity. Adding any turf tea/compost tea product at this time will significantly reduce the efficacy of the CGM as it wil break it down very very quickly.

Look to University of Iowa studies on CGM as they are the leader in this area.

Deerslayer...lol...studies? Do yourself a favor and read a whole study...some of us have actually done them!

ntbio--you keep referring to the university AG studies. Can you provide a link to them? I assume by AG, you mean the Agriculture college at some university. Which university? Iowa?

Thanks in advance.

Ntbio, yes I believe that MSMA was outlawed in August, 2006. (I didn't look it up so I may be wrong). This coming spring would be the first opportunity to perform new studies. I don't understand your logic.

I already explained my handle to you. Do you have a problem with reading comprehension? If so, I'll cut you some slack.

I don't understand people that think that there is something wrong with acquiring knowledge from university and other relevant studies. I think it is much better than making up information or using anecdotal evidence. Obviously, you disagree.

Your GA information is not very relevant to a poster that lives in Montana. I tried to post info that was from zones that are as near as possible to the poster. I realize that you don't pick up on such subtleties. Who said anything about air temperature, anyway?

Post a link that materially disagrees with with my previous posts and I'll be happy to debate you.

-Deerslayer

In reply to a question by deerslayer asking ntbio to provide links to university studies in apparent conflict with deerslayer's point of view, ntbio replied with the following: Deerslayer...lol...studies? Do yourself a favor and read a whole study...some of us have actually done them!

I've given up on ntbio providing links to studies. I've asked, bpgreen has asked, deerslayer has asked. This is the first time I've seen a suggestion that ntbio might be an academic performing research.

Having said that, in this case I think what ntbio has tried to say (with the "bracketing the algorithm" paragraph) is that if you put the CGM down in the spring when soil temp is 50 degrees F, since it is spring, the soil temps are likely already on the rise and you have 6 weeks for the CGM to work. In that time period the soil temp will rise through the effective range and you will catch the germination of the early spring weed seeds as well as the later ones.

I can't find a satisfactory definition of "bracket" or "bracketing" except from photography. What it refers to is the concept of doing something several times with a slightly different setup. In photography they take pictures at different settings to get the light just right. In this case, with soil temps, suggesting a lower than the temperature range suggested by deerslayer, ntbio would be bracketing the experiment.

DCHall, I think you're giving ntbio too much credit. His other comments are not likely to come from an academic doing research. For example, he shows disdain for people that look up facts to support their arguements.

In academia, an exhaustive review of prior similar studies is performed before primary research begins. It's common to see these studies footnoted in the paper. Studies that have already been done are not usually redone unless the original study is being challenged.

Besides, people engaged in primary research don't castigate others because they support their statements with references to studies.

DCHall, I've seen you take shots at academic research in the past. Please don't hold up ntbio as an example of someone that performs academic research. Based on ntbio's other comments, I think it's much more likely that he's in the anecdotal camp.

Ntbio doesn't provide links to support his statements simply because the links don't exist.

-Deerslayer

Obviously, Iowa is just another "flyover" state to many who post here...and few know much about it...unless you are running for POTUS and spend your weekends in the Hawkeye State...(grin)

Everything you want to know about CGM is at the link below to Iowa State University in Ames, Iowa. That's where the whole CGM story begins.

There are other links at the ISU page to further research on this product.

Personally, I think CGM is an expensive and unsatisfactory pre emergent herbicide for use on residential lawns. It takes several seasons to get results. And given how impatient most of us "lawn care wackos" are for quick eradication of weeds it is too slow to work on a large crabgrass or Poa problem.

Just my 2¢

Pete in Iowa

Here is a link that might be useful: Iowa State University CGM story

Iowa, I agree that CGM is not as effective as synthetic preemergents. However, it's the best alternative for people that need a pre-em and want an "organic" lawn. Many people use CGM for its high N content and consider the pre-em properties of CGM a bonus.

-Deerslayer

My backyard is full of weeds it's not funny, I don't know what to do. What preemergents can I use NOW to stop to weeds from spreading even more?

Thanks a lot.
Msjam

Organics rock! All my neigbors are interested in how I maintain a green lawn all year. This spring we are going shopping for corn meal together.

I see lots of debate (not so pleasent at times) over when to apply CGM in the spring. All I know is when the forsythia bloom spring is well in motion. I look to bracket this time with corn meal. (Late april in MA)

In my opinion spring is the time to place copious amounts of corn meal on the lawn (10-40 lbs/ft^2). I do it in April and one month later in May in New England. Do I believe that this will suppress all crabgrass germination? No.

Do I believe that it will improve the health of my lawn, allowing better competition of grass (CRF and K BG) vs. weed and help surpress some fungus? Yes. Do I spray milk at the same time to help with red thread? Yes.

We all live in different areas and most are well versed in googling the web to find relavent information. We must find via trial and error what works best for our own piece of America. Organics takes years but results are noticable in months. Don't expect perfection but a weed hand pull here and ther goes a long way.

I am a Chemical Engineer and could easily be engrossed in theory and these N=1 studies we find on the web. I find that while the web provides a vast vault of information and theory, only through trial and error can one find what is best for their lawn.

Corn meal in spring, Alfalfa 2weeks prior to seeding or late August and soybean meal to overwinter seems to work well. If your lawn and soil has a pleasent smell you got the right stuff. University studies are usefull but none of us have a lawn protected by a green house.

JMHO
Gary

"In my opinion spring is the time to place copious amounts of corn meal on the lawn (10-40 lbs/ft^2). I do it in April and one month later in May in New England. Do I believe that this will suppress all crabgrass germination? No."

Most people do not believe that corn meal suppresses crabgrass germination. If you think it helps, fine, it's your lawn.

-Deerslayer

Personally, I think CGM is an expensive and unsatisfactory pre emergent herbicide for use on residential lawns. It takes several seasons to get results. And given how impatient most of us "lawn care wackos" are for quick eradication of weeds it is too slow to work on a large crabgrass or Poa problem.

I agree. To me, and from what people have reported here in GardenWeb, the ONLY way to eradicate weeds is to water no more frequently than once a week and to grow your grass as tall as your mower (and your spouse) will let you.

obviously, having been spoon feed the links to the IOWA study and a few other posts regarding CGM is not hitting home...this an ORGANIC lawn care forum...CGM is the ONLY pre emergent that shows some efficacy. (There are other universities that have done studies as well.) It is not perfect and does require some timing issues..but it is orgianic and it is OMRI listed.

And deerman...corn meal is NOT corn gluten meal......EVERYONE do NOT USE corn meal ... you must purchase "CORN GLUTEN MEAL 60% Protein"....make sure its labeled...

MSJM...pre emeregents addess seeds beginning/germinating...post emergents address established pests/weeds. They are controlled seperately. There are alot of very good orgianic lawn care providers in DFW...call one up! they will come out for free or a small fee to discuss your lawn I am sure! Make sure they are licensed, insured and have some orgianic certification like SOUL.

Oh, and most certainly, look to AG universities in your area for studies on these products and timing...they are a good starting place.

"And deerman...corn meal is NOT corn gluten meal."

Nutbio, if you are referring to me, where did I say it was? You seem to have a major problem getting your facts straight.

-Deerslayer

My subtle point was that we're getting to an age where the preferred solution to every garden problem is a product, a spray or a powder/dust, that will kill whatever problem you have. My preference is to use good cultural practices to prevent pests and disease. Then in the background I follow a program of organic materials over the long term to give the plants the health and strength they need to fight off pests and disease. I'm still using organic materials, but I'm generally not reacting to sudden problems every few weeks. In my program CGM makes a great fertilizer but not so great a preemergent seed controller.

ntbio: it was grayentropy who got things confused, not deerslayer. He was quoting grayentropy and trying to correct him.

aye, theres the rub...

"My subtle point was that we're getting to an age where the preferred solution to every garden problem is a product, a spray or a powder/dust, that will kill whatever problem you have."

The overall health of the turf is THE focus of organic lawn care.

Grayentropy,

Glad to see a New England post. I started organic in July of last year, so I have not applied CGM yet. Late April is a good time for Southeastern Mass? When you say you spary "milk" for Red Thread, do you mean dairy? cows? Regular hose end sprayer? Our mild winter thru January has caused Red thread all over my KBG.

Thanks

Dan T

dantis,

I dont use CGM due to the cost but do place corn meal/cracked corn in early spring to feed my winter-starved soil. I will probably add it in early April depending on the weather at a rate of 15-20 lb/1000 ft^2.

I also spray cow milk at a rate of 3 oz/1 gal from my hose end sprayer for red thread. As we often get alot of rain in the spring, I also use my kids leftover cereal milk to soil dose outbreak areas.

You have redthread already? I still have ice on the grass.

Aloha. Has anyone had experience with CGM in Hawaii or similar zone? I have been promoting the use of organic mulches to manage weeds in new groundcover plantings instead of the pre-emergent Ronstar (mulch is new for mainstream landscapers here). I am deeply concerned for the soil and groundwater health as well as my own. My hands are in contact with the soil 6 hrs a day. I want to try mulch and CGM and would appreciate anyone's experiential knowledge. Also, in the establishment of a Seashore Paspalum lawn through stolons, has anyone had success without Ronstar or similar?

I enjoy this shared knowledge. Thank you everyone.

I found a local source for CGM - 60% 40 pounds for $14. How much coverage would I get per 40 pounds? I'm looking to put this down this weekend.

I noticed some MA posters in this thread. I am still looking for feed stores in eastern MA that would have CGM & alfalfa meal.

I did purchase some over priced CGM at a local garden center. I did my first application 4/1/07. Here is my convoluted reasoning: Fist to take advantage of the rain... Dr Christians claims light watering is necessary. The pellets are still visible after 1 day of rain. Product instructions say apply before forsythia blooms. From my reading it is too late once the weeds emerge above the soil. I plan to reapply in 3 weeks; maybe IÂll see yellow blooms then. One last application 3 weeks after that, mid May.

This will be my first usage of this product; the downside is that I applied some very expensive N.

I have used Corn Gluten Meal for several years now and I am pleased with the results. Is it the best preemergent available on the market? No, I don't believe so! However, I will only use organics on my lawn...so it's good enough for me. I also like that it is feeding the soil as well as my lawn. Is my lawn completely weed free? No, but I do get plenty of compliments on it from my neighbors.

Tumblenes, where are you in Eastern MA. I'm in Grafton and have three grain suppliers. If your near Boston (go Dice KKKKKKKKKK), I would recommend checking in with you local Agway, lumber store and any farm and garden store you can find.

You can usually get Alfalfa feed as rabbit food in most stores although it does have alot of Salt (0.5%). I figured with the 48" of precipitation/ year we normally recieve in MA the salt would wash out of the soil. I added 20lbs/1000 ft^2 last fall.

grayentropy, Near Boston, last year I traveled to 2 agways, but niether had alfalfa meal or cgm. One of the place was near 495 & rt 2. Garden stores are just begining to carry alfalfa based fertilizers at $25...

Try this link (add your zip) and call ahead. If they don't carry it ask if they can order it for you.

Good luck

nice!