The goldfinches found the zinnias.

They're seed eaters, mostly — that's why they come to the coneflowers as the flowers fade and the centers dry. Same with the zinnias in a few weeks. If I let a patch go to seed instead of dead-heading, the goldfinches will strip it down before winter.

Lauren says the trick is planting in patches, not single stems. A single coneflower is invisible to a goldfinch. Six of them in a group is a target.