How do you prune mums?
Certified GKH Gardening Expert
Usually, these plants are cut back in the fall following a few frosts. Stems of mums are pruned back to 3-4 inches above the ground. New growth appears from this in spring. If you are not able to cut the plant back in fall, you can do so in spring if there is still old, dead growth present. I would not trim off the new green growth.