I have some Echinacea, Gallardia, & Coreopsis that have taken over, and I'd like to relocate some or all of them to a new location. I would like suggestions/advice on whether or not it's okay to do this now, in the Fall, or if Spring is best. These plants were grown from seed 2 years ago, and they got much larger than I anticipated.

Also, I welcome recommendations for the soil in the new bed. I have clay soil, so I plan to dig most of the clay out and replace it with top soil (with pine fines), mushroom compost, and maybe some peat moss. What do you guys use for soil amendments?

I like to move things around in fall if possible, so their roots have a chance to get re-established and also because there is just so much to be done in spring. I cut the flowers back to about 3", chunk them out, and mark them with a stick until they re-emerge in the spring. I also make a note in My List here at NGA where I relocated the plants so the stick is just a temporary marker (I'm not a fan of permanent plant markers in the garden, they remind me of graveyards). You may want to leave the echinacea until spring to move so the birds can enjoy the seedpods over winter. Good luck on the gallardia, mine rarely over-winter and I tend to treat them as expensive annuals (still trying to find a cultivar that will be reliably hardy for me).

Deb, try the gallardia from seed. I couldn't grow (keep) the expensive coneflower plants that I kept buying. Then, I saw a pack of seeds and decided to try it. They've been coming back for me four years now, getting better each year.

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.

Ha, I was working in my flowerbeds this morning and realised I planted gallardia seeds this spring! I left the seed lot laying beside where I planted them. The seedlings are still only about 3-5 inches tall. I doubt if they will flower this year. But the coneflower seedlings were the same. They didn't flower the first year. So, there's still hope!