That is a fine,organic method to killing weeds and starting over. As you learned from your experiment clear plastic works best. Sort of like a green house effect. Lets the suns rays through and just bakes everything underneath. As you mentioned, it's recommended that you scalp the lawn first, water, then cover. The water helps heat up the soil.
Paul Tukey suggests that pool liner works even better. I have no experience with that material, but it is a bit cost prohibitive. To really kill all the weed/weed seed it will take about 6-8 weeks. In the fall, be sure to add organic matter, Soybean meal, alfalfa, corn meal, ect... also topdress with compost as the soil will be nearly biologically dead at that point. Overseed in the fall and by next spring you should be in good shape.

To prevent future weeds, in addition to a thick, healthy lawn, read about applying Corn Gluten Meal as an organic per-emergent.

Here is a link that might be useful: Soil Solarization

Thanks for the additional information, SC. I think I will try the reseeding in the fall over the winter as you suggested, and feed the area as well. I've been making my own compost and compost tea but I will also look for the amendments you suggested, especially the corn gluten meal to deter future weeds. I'm wondering where I might get my soil tested here in Michigan. I want to do a targeted feeding.

There is a chance I may be moving before all of this happens, and if that is the case, I will be a little sad. I love a good challenge and creepy charlie has been all of that!

I've only been a member of this forum for a short time but have already learned much. I'm now watering once a week or less and mowing high (except for the areas I'm killing). Thanks to all!

Michigan State University Extension Office would be a good place to get your soil tested. Be sure to test for organic matter % as well. Sometimes that is an extra test, but usually only an extra $5. Umass costs me about $20 bucks plus shipping.

See my last reply on This Thread for an explanation on how/when to apply Corn Gluten Meal.

Michigan State Universities Cooperative Extension Service offers soil testing that includes amount of organic matter, soil pH, P, K, Ca, Mg, and CEC for $13.00 per sample. Your county horticultural agent will write recommendations, organic if you specify that, to correct any problems they see. Some are better then others and some are organic growers themselves.
Soil solarization can help, and as you discovered clear plastic is more effective then opaque. Some state that two plies of plastic should be used, but all agree that the soil under the plastic needs to be wet.
The edges of the plastic sheet need to be well sealed, to contain the heat generated, placing rocks, bricks, boards, etc. will not work well.

Here is a link that might be useful: About soil solarization

Thanks for the information on where to get my soil tested! The price is very good and I like that I may be able to get an organic recommendation.

Soil solarization apparently worked so well for cc because of charlie's shallow roots. Even though I did not wet the surface and did not have it totally secured (buried) at the edges, it still killed it all except for the very edges. I also noticed that in some areas, it did not completely kill the grass and it's growing back with no cc. It's been an interesting adventure. I wonder why this method is not recommended for getting rid of this pesty weed (organically) more often.

I've got a bolt of plastic and will be doing a larger area over the next couple of weekends. By the time I get the cc killed I should have my soil sample results and can plan my lawn's nutrition.

It will be so awesome to have a lawn I'm proud of, without chemicals. There is not a single lawn company in this area that performs organic lawn care so I'm having to do all of this myself (and I'm feeling a bit overwhelmed) but finally seeing some rays of hope helps.

That's great news! Unless you are on a specifically organic forum like this one, mentioning the use of solarization will get laughed at and cause heated arguments, so no one mentions it, but as you have seen...it works.

I can understand why lawn care companies typically do not do organic lawn programs. It takes time and patients to build up the quality of the soil. People want instant gratification. They want to see the lawn care company at their house today and have an electric green, weed free lawns tomorrow, with poor soil. That's only possible using synthetics. Additionally, people seem obsessed with cutting their grass way too short, bagging clippings, and watering as frequently as possible. However, those of us who understand what grass needs to be successful, and are willing to take the time to build up the soil's nutritional value/life are rewarded.