Overgrown Coreopsis (?)

Asked January 11, 2019, 6:53 PM EST

I am pretty sure the uploaded pictures here are of Coreopsis. Part of the backyard was professionally landscaped in May 2018 and these plants produced yellow flowers all summer. They have spread and look unkempt. Today, the landscaper said that they were seeded from wild flowers that I previously planted in that area and that the company workers did not plant them. Can you advise me on how to care for them, especially if, when and how to trim them back without getting rid of them completely? They are impinging on the plants that were intentionally installed.

Thank you. Karen Silverton, Oregon

Marion County Oregon flowers: annuals and herbaceous perennials

1 Response

Hi Karen. The leaves I see in your images do look like coreopsis. I invite you to look at flower images to corroborate that. Regardless, some coreopsis are annuals and some are perennials. If perennial, coreopsis have similar care and maintenance needs as other perennials. In part, decide your end game for these plants. They can be sheared back a few inches to force fall bloom but don't prune all the way back to the crown for winter; stems left standing will protect the crowns. Be prepared to divide them every two to three years after blooming in the fall or in early spring. To divide, work around the perimeter of the clump with a sharp spade or garden fork and lift the plant. Tease and pull off sections around the perimeter of the parent plant, selecting sections with three to five vigorous shoots and root systems, discarding the spent center of the clump. Finally, please share the divisions if you do not wish to keep all the plants ;)