Answer: Mums may be pruned back to about six inches in the late fall after frost has killed the tops. Then, in spring, prune the old stems off as short as possible. The reasoning behind this is that the old stems provide a little bit of extra protection for the plant during the winter. During the growing season, periodically shear the plant lightly or pinch back the growing tips to encourage branching. Stop doing this in mid July to allow time for the flower buds to form and bloom before the cold weather sets in.
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