I think this is typically now it's "spreading" time so good time to get them into the ground. In hotter climates it's supposed to have a fall flush if sheared back, but I've never had any luck

We have coreopsis for the first time this year. It would be fine with me if they ran amuck throughout the garden! That being said, I am still unsure about deadheading or shearing back. Right now I have about half flowers and half deadheads. I'd love to see them bloom again (and again), but need some advice. Thanks Glenn

Deadheading is supposed to help encourage a sporadic rebloom throughout summer. Auriculata is supposed to rebloom in fall whether you deadhead or not. First year plants tend to rebloom more consistently without deadheading.

Instead of deadheading each bloom individually (tedious), you may want to shear it down about halfway now, as that will encourage the best fall rebloom.

Same here, I shear back and get more booms late summer

I rarely dead head my established coreopis ('Cosmic Eye') and the blooms keep coming till frost. Even if more blooms would result from a complete shearing there is no way it would compensate for the duration without any flowers. It is summer and I want flowers now and continuing.