I live in Colorado and usually have to work with compacted clay soils. This however, is a new one for me! I have an area under an old corner patio that I really want to plant in. The compacted clay is topped with about 2 in. of coarse builder's sand, which supported the paving stones of the old patio.

We have taken up the pavers, removed some small rocks, and measured the sand, but are now scratching our heads.
Can we till the sand plus some compost into the clay and use as-is, or is there something better we can do?

I anticipate not being able to plant a wide variety of beauties here, and am ok with sticking to natives if needed.

Thank you for any help you can give!

Edit: Thank you for your replies so far. As far as how compacted we are talking about- when the clay is wet and we are able to even get a shovel into it, the resulting clod is like a brick. I actually dug into it to plant last year and the displaced 6" mound of clay is still visible... a year later... despite trying to wash it away every time I watered. We are talking serious compaction and concrete-like soil.

Tilling the sand and compost into the clay should improve drainage, but I would suggest doing a soil percolation test beforehand to see how well the water drains. This should give you an idea.
https://www.youtube.com/watch?...

Sand. Clay. Compost ! Yeap !
A little manure.
And.... Start that roto- tiller up ###
😎😎😎

Compacted clay sucks, and I've run into clay that had been compacted in multiple layers, and digging down to sticks and logs found wood that hadn't begun to decompose due to the lack of air.
Not sure what good a drainage test would do, compacted clay doesnt perc....
I'd dig the sand in as deep as I could, and hope for the best...

In that garden with the layers.... I never could get deep enough for the soil to drain.... It grew really nice wetland plants....

Eventually, additional wok was done... With heavy equipment on the garden (again!), and an auger was tried... Kind of useless, because after the auger, a bobcat was used to level everything out... Further compacting that mess....

Some people just won't listen....

Bye the bye, a tiller is useless in compacted soil.... Just bounces... Tiller won't work until you break up the soil, and then....you don't need the tiller....
I firmly believe that a tiller is probably one of the worst tools you can use on a garden.... it kills the worms, destroys soil tilth, kills the mycelium, and... Brings up the seeds to the surface where they can germinate.... So.... If you want weeds.... Run the tiller.... Other wise... Maybe just don't bother.

Go out there with a shovel and mattox, when the soil is moist.... Winter is a great time here.... Where you are... Probably now is fine.

Soil compaction is in the eye of the beholder. A perc test will give you an idea of how badly compacted the soil really is and a better idea of how aggressive the remediation needs to be. The compacted soil may also be a relatively shallow layer, depending on whether the surrounding land is also clay or if the soil was hauled in for fill purposes. I would want to know before I put a lot effort into correcting the problem.