I don't think either of these methods will faze bermuda grass. Smothering may have some effect, but it will persist. Cover crops?? -- I can't imagine that you could even get a cover crop to seed properly in existing bermuda.

Black plastic may work, if you are patient enough, but I think herbicide is the only way to get rid of this stuff. I think it is a challenge even with Roundup.

see my suggestions to the Bay area grasses perosn...
everyone wants to farm (and making a meadow is more like farming than gardening a perrennial bed) and yet wants to have great new ideas that farmers never thought of... like laying plastic all over their fields... or wet newspaper for a vew years (if your homeowners associatio will allow it along with your clothesline in the front yeard)
sorry to be sarcastic but i've tried all this so i am the first idiot... what i don't get is how those "wildfower seed companies" can continue to bambozal people. If you want a pure stand of grass then seeding can work... but if you want more the simple rules are... first kill all existing weeds (is handweeding an acre cheap?) then smother all existing seeds (the esaiest way to do this is to use sand and compost. This is not cheap but at least it actually can improve the soil.. and you do need good soil to grow what you want rather than what you do not want.
and lastly, if what you are gowing is an annual, and grows fast and has no competition then seeds can work, especially if you hydroseed and have irrigation. If not then you shoudl use bare root plants, planted in the fall. And still you will need to weed or use chemical surpessents and you will need to water through the first summer.
Ultimatly it is beautiful and requires not a lot of work time, though the work it does require it requires that you do it without delay, and it requires constant monitering to keep it right.
Is there an arboreatum near you who has established a field like you want? ask them the cost and then ask the installers exactly waht they did...
just my experienc..

Georgia,

If you are planting a small garden spot, then you may be able to use the smothering/mulching/bare-root planting methods suggested above. However, herbicide treatment before using these methods will almost certainly give better results.

For larger areas, there is a large literature and a considerable industry devoted to prairie plantings by seed in the midwest. (I assume that similar methods would work for you in the southeast.) These almost always rely on repeated herbicide treatment during a full growing season, seeding in the fall, intensive weed management (mowing, hand-pulling, etc) for a couple growing seasons before the prairie perennials become establshed, and continued manaagement by periodic burning and/or mowing.

Here is a link to a prairie restoration guide from one of the midwest nurseries with an excellent reputation:

Here is a link that might be useful: Prairie site preparation -- Prairie Nursery

I wouldn't use Round-up. I've read articles that Round-up has long term affects on the soil and will harm the new seed. Try Ornamec. It works on the grassy types of plants, but won't hurt any seedlings you put out. We have a wildflower meadow across from our elementary school which became overgrown with Johnson grass and other unwanted non-native grasses, so the city helped us out by using the Ornamec - which was recommended by a landscape architect from Texas Dept. of Transportation who specializes in seeding the roadsides with wildflowers - then after a couple weeks the city came back and tilled everything. We did this over the summer months so the Ornamec was more effective in the heat. We waited about a month before scattering wildflower seeds. We now have beautiful wildflowers during the entire growing season. There are some grasses in there again, but these are mostly native grasses - no Johnson grass that I have seen. I don't mind the grass growing in a meadow. I think it is an important part of the whole meadow. I mean, it isn't a home garden where the weeds should be kept at a minimum.

Thanks for your suggestion Denisew,

I have never heard of Ornamec. Is this something one can purchase where landscaping supplies / lawn chemicals are sold? I'll have to look into it some more.

Just a quick response to Denise's herbicide suggestions.

She is wrong about Roundup. It is becomes inactive once it contacts the soil, and will not prevent seedling germination. It is only effective by direct contact with live, growing tissue --typically leaves or cut bark. If used properly (which may involve more than one application before you plant your seed) it should take care of your berumda grass problem

I don't know much about Ornamec. It is sold as a grass herbicide for use in ornamental beds (obviously, for beds without ornamental grasses). The web site I found does not specifically mention bermuda grass, which suggests (to me) that it may not be effective on your problem species. You should also check whether it has any residual action in the soil, where it could potentially affect any grasses that you might plant in the future.

Here is a link that might be useful: Ornamec

Try www.prairienursery.com