I did that exact thing this morning. Yes, you can divide the plants into pieces so they fit into your pots. So long as you cut them back (which it sounds like you already have), keep them well watered and keep the pots in a shady spot they will be just fine. Coneflowers transplant and divide pretty easily as long as they have enough water. Mine are surprisingly thirsty after I move them.

I thought that is what I had to do but a search only told me how to grow them, etc. I dug up a celadine poppy plant today and I was able to divide that into about 9 plants..

Ever divided a Pinks(Dianthus)plant? I tried but could only knock a lot of the soil it had around it and put it in a pot that would fit it and packed potting mix around it..watered it good..Hope all I've planted up makes it. My problem is lack of space in shade to keep it. I have to keep moving plants around following the shade..

I know what you mean about dividing dianthus. Sometimes the plant makes a big wide mat and there are not too many obvious stems going down into the ground. If a nice piece comes off I will plant it separately, but most of the time I propagate it by moving the little seedlings around.

And I do the same thing with moving plants around. I don't have any shady places that are also near water, so it's a bit of a hassle to keep things happy in pots for very long.

I'm going to transplant a few of my coneflower today - the weather has finally cooled (it's like a spectacular fall day here in SE Michigan, not what you'd expect for August...), which is probably more important for me than the plants :0p