You could try a wild flower seed mix, they make them for all types of soils. But you will still have to water it until it gets established. Check out this link below, and search seed mixes for 'claybuster' mix.
Sarah

Here is a link that might be useful: Wildflowers for Clay Soils

In the high deserts of the Great Basin where even the sage brush is sparse and sickly a wild flower mixture from a local big box store does very well. There is one plant with teeny tiny white flowers that even has to be thinned or it will overgrow the others.

Marigolds and calendula do well too.

Gloriosa daisies (Rudbeckia hirta) Are the only things that will grow in a patch of property that I fondly call 'Hell' Everything else there dwindled and died with a whimper. The daisies are spreading in fact! And are beautiful all summer long! Throw seed down in the rainy part of the year or water until they sprout. No mulch. No supplemental water. Pure clay in full sun.

Butterfly magnet.

The meanest annual I've ever grown is {{gwi:1034}}. Small yellow flowers, and lots of big, thick dark purple-black spines on the stems (and leaves!). Makes fall cleanup an adventure.

More practical advice: Have someone build you a couple of raised beds where you can garden more comfortably in amended soil and grow whatever you want. Don't try to do too much too soon - gradually amend your other growing areas while looking at your landscaping as a long-term project.

Could you maybe cross a porcupine with a wolverine, then just plant it .... in gravel & broken glass? I know the last poster mentioned annuals, so I'll hope you don't really care one way or t'other - just so they're tough - b'cuz these are both perennials. Just a thought.... I sure hope someone comes along that's more help than I was.

Al

Datura inoxia thrives here on neglect. Cosmos too. Lantana should work as well. You may need to start them in pots. The cosmos are used here in NC as roadside flowers along the interstate.

The good news for you is that some of the best agricultural sites in the US consist of red clay soil. As long as your property DRAINS sufficiently, it's no big deal to tame this stuff. Trust me, I know from personal experience!

Rather than looking at the big picture, why not focus on one small portion of your landscaping....one area that will make you happy each time you look at it? The ordeal of it ALL won't seem so insurmountable if you attack it a little bit at a time. Eric had the right idea in his earlier comment.

I'd surely suggest that you turn as much of your property into something useful (and easier to take care of) instead of grass. Large landscape beds and tree collections can all be mulched to keep weeds down and to add to their attractiveness. Assorted mulches eventually break down and begin improving that soil, too.

When we moved to our present home, this yard was pretty discouraging, too. I was horrified at this brick hard stuff we were supposed to grow stuff in. We tilled in a fair amount of aged bark fines and compost ONLY into those areas where we planned to add landscaping (shrubs, perennials, and annuals). The several trees we added, as well as the grass (mostly weeds when we got here), simply had to make do. Guess what? Trees planted directly into that hard red clay, with no amendments at all, grow like crazy!

Those beds were amended once. We top dress with mulch and compost annually. We aerated the areas meant for grass heavily, then sodded with a hybrid Bermuda. After a very brief growing in period, the grass began to thrive like crazy on top of that red clay. Again, with very little watering (and we don't have an irrigation system).

Come to find out, there's nothing difficult about growing in red clay soil. Well, we use a heavy duty auger to plant things rather than a shovel... but so what? ;-) Our plantings have thrived with less water, less fertilizer, less fuss than I have ever experienced in all of my years of growing! Go figure.

Nasturtiums are a good option for you~Get the tall assorted varieties and they will ramble and trail all over the place.I'd wait until mid April to plant them there in your zone,but they grow quick and are very inexpensive when grown from seed.They bloom best without fertilizer too!

I know of nothing that will grow on hardpan clay, if crabgrass died.

Think long and hard about planting agressive plants -- one day you will have time to properly garden and the agressors will be all over your nicer plants.

I would just make small improved beds that grow nice plants for now and keep the rest mowed. You can keep extending the beds in a 'lasgana' gardening manner until the little beds become big beds. Start a compost heap. A cold compost heap will break down into mulch over time.

Nell

do some reading about "lasagna gardening" - that's a good way to easily build raised beds with terrific soil, and it can be done on the cheap and will smother out the crabgrass underneath.