Do you cut back asters after flowering?
Similarly, when should asters be cut back?
Cut back aster plants in late autumn, after the first hard frost. Snip off the stems 1 to 2 inches above ground level. Rake up and discard the pruned matter into a green waste bin to discourage insect pests from colonizing the soil around the asters.
Similarly, you may ask, what to do with asters after flowering?
The plants should be cut back after flowering and then, if possible, stored in pots in a cold frame or greenhouse over the winter. Keep the pots moist but not sodden, and do not apply extra heat. When there is the first sign of new growth in spring, remove the plants from their containers and repot in fresh compost.
M.B.: You don't have to do anything in the fall but enjoy your asters. Leaving the faded blooms and frost-blackened stems later in the season actually helps protect the roots from winter freezing. If you are a tidy gardener, it's OK to cut asters back completely after they bloom.