I would be adding compost to the soil. I had clay soil here, and they didn't do as well as when I added compost the next year. Also don't plant too deep. I made that mistake one year.

You can grow them in clay. I do--quite well. Don't plant them very deep, an inch or two. Full Sun, lots of water. Fertilize frequently and they'll do just fine.

I too have clay soil but I made sure to ammend my soil also .. with clay if it dries out well .. it can be quite a mess. Ammend your soil .. you will be rewarded with huge blooms and many rhizomes in the fall :o)
Laura

You sure can. But like jroot and WhistlingDixie said, don't plant them too deeply.

However, if you have compost I would amend at least the backfill with it. It definitely won't hurt to dig your hole deeper and wider and mix the backfill with compost. I guess you could call that 'spot amending'. :))

And mulch with a rough compost as well. It will help to keep the clay soil from baking into concrete (altho that really won't stop 'em), but will keep the soil softer and will feed not only the soil as it breaks down, but will feed the worms as well.

Jenna