I've only tried perennial coreopsis once, but didn't have good results, either. The annual varieties do very well for me, but not the perennial. Similar results with Rudbeckia. Annuals germinate well, perennials not so much. FWIW.

Martha

My rudbeckia have always been a bit slow to germinate, the perennial ones a bit slower than the annuals. I've never tried coreopsis.

Karen

coreopsis grows like a weed! They are a little late to appear in the garden. My ruds are just starting to pop with not much germination.

they will catch up.

Mine are just starting to sprout, particularly, the one's I purchased from the vendor. However, the seed, I harvested from garden are up and running.