This is an image of invasive teasels on September 10th. On July 30th, to prevent seed production the flower heads (about half open at the time) and the upper half of the plants were cut off and removed. The plants were cut above where the leaves had started dying. Despite being cut during flowering above where the leaves had started dying, these plants (and others) had the energy to send up more blooms. In contrast, the plants that were cut at ground level on this date, and after, did not send up new flower shoots.

The lesson is once teasel has started blooming, it is best to cut it off at ground level to reduce the possibility of it creating more blooms.