Question: In your opinion should chrysanthemums be cut back in the late fall or spring?
Different sources say different things about what to do with mums after they are browned by frost. One source advises to cut them back in the spring; another says to cut them back to about 8 inches after they finish blooming in the fall.
In my experience, either way seems to work. I usually leave them until spring in my garden beds, which tend to be informal (some might call them “messy”), and often the new leaves start to come up from the roots very early — as early as February, if we have a mild winter. At that time, I cut back all the dead stems and divide and move clumps where necessary, and they grow happily and vigorously through the spring and summer. I cut them back a couple of times during the summer to delay flowering, and they start to bloom in the fall.
If you prefer a tidier look throughout the winter, cut off the blooms after they turn brown. They will rest during winter and be ready to pop up again early next spring.