they'll do ok with minimal care depending on where you get the seed - but they won't be enough to keep the grass or other weeds down at least for the first few years - i have a couple areas of my yard that i've done that with - i still have to weed out the grass and separate the wildflowers (by that I mean i'll end up with one part of it's that's very thick with wildflowers and another part that's practically empty or a whole bunch of black-eyed susans in an area and nothing else) - instead i'd handpick a couple wildflower seeds you want that will grow in that area and caste them - that way you'll have a little more control over how intermixed the plants are

I saw a lot of black-eyed susans, and daisies in the area- I assume they do well there. Just those two would make me happy!

Watch the wildflower mixes many are just european flower seeds. There are some good mixes out there but if you like certain plants see if you can find some at the end of the season sales that you find at nurseries. Mix in a quart or two of sand and spread. Many of the perenials and biannuals will come up this fall and may flower next year. The sand helps keep the plants from clustering. There will be some plant that come up from a cluster because that is the way their seed is. Think of beets one seed actually has five or more seeds clumped to gether.

Be certain to mix some annuals in the mix depending where you will be in SC you may have time for them to flower or they may wait until next spring to germinate.

As you find new native plants that you wish to add spread the seed of those in the spots that have nothing growing.

I would pick a few types of flowers you like and are common around your area and plant those. I agree with kandituft - instead of mixing all of the seed together, I'd plant an expanse of one plant bordered by an area of a second flower, and so forth. You will probably be happier with areas of 10 to 100 square feet of each flower type with only incidental mixing of other species. This will allow each type to grow at its own pace and height without being overshadowed by others. There are lots of flowers that could be good choices. I'd also throw a native grass like little bluestem in with all of the flowers. The grass will help control erosion and fill in between the flowers while creating winter color with its reddish winter leaves.

check out americanmeadows.com I bought seeds from here and have had pretty good luck. I did the fall planting last year. The black eyed susans flowered this year, some of the lance-leaf coreopsis flowered and lots of plants have grown so should be great next year. Blanket Flower has done ok. Only problem I have is Wild Perennial Lupine. I have tall things, no flowers, but don't know if this is them or weeds! I can't pluck them out if I don't know can I. Everything shows the flower, not the plant itself. I believe I will get purple coneflower next year as little plants are similar in the area I planted them.

Check out lupines many are biannual. Will come up one year bloom next and probably die.