Question: I have a flower garden that includes black-eyed Susans, bachelor's buttons, and tall phlox. How do I treat them to promote long-term bloomng? Does trimming the plant help, and how soon and how severely can I trim after the blooms fade?

Answer: Annual bachelor's buttons will rebloom freely if trimmed back to remove the spent flowers. Cut the flowers as for a bouquet, just above a branch or leaf so as not to leave bare wiry stems sticking up. Black-eyed Susans will bloom naturally over a long period, but if you deadhead the plants by cutting them back by about half once the main flush begins to fade, you may stimulate another (smaller) flush of bloom in the fall. Some gardeners simply allow the seedheads to remain and consider them an attractive fall and winter feature in and of themselves, and the birds will enjoy the seeds. The plants would then be trimmed back very short in the spring.

Tall phlox will bloom over a longer period if spent flowers are removed one by one. In general, phlox (except creeping phlox) should be trimmed off very short in the fall once frost has browned the tops. All of these plants will give their best display in full sun with rich soil that is kept evenly moist (but not soggy).