How to Prune "Sonata Mix" Cosmos Bipinnatus
- 1). Deadhead the Sonata Mix cosmos frequently throughout the growing season. Snip the dead flowers' stems back into the foliage.
- 2). Cut the entire plant back to within 12 inches of the soil every month after flowering. This prompts the cosmos Sonata Mix plants to produce new flowers.
- 3). Prune the cosmos back 3 to 4 inches tall as soon as the plants develop their star-shaped seed pods. Cut back the entire plant, including the seed pods.
