Hi Jessie,
I have lots of Coreopsis and Gaillardia and I move them in the fall and spring (mid-Sep and late Feb in my zone, 9b). I usually divide them while I'm at it if they are more than a foot round, to take care of two things at once. I have never been able to get more than one bloom from a Cone Flower, once, and then it died like all the rest. I'm not sure why. Everything else does fine. And that won't stop me from trying!
My soil has a lot of clay, too, and I use compost to feed and cover. Weeds can be pesky if you turn the soil too much here, so I just cover the soil with a half inch of it and don't dig it in. It is gone from sight in about six months.
If you are not afraid to possibly lose some plants, you probably could move the Gaillardia and Coropsis now, if you keep them from the sun for three days or so, and water very well a foot down, keeping them very well watered those first two weeks. When I try this, I use a long screwdriver (don't tell my husband!
) and if it goes a foot down with no trouble, they are watered enough. I do that for the first two weeks. That works for me when I just can't wait to relocate later.
