Answer: Many gardeners pinch back or shear off their mums every few weeks starting in early spring and continuing up until about the fourth of July. This forces the plants to become thick and bushy and also delays flowering until the fall. Since yours are already flowering, I would enjoy the blooms.
You may be able to get a second flowering from your mums if you pick the flowers for bouquets and then cut the plants back by about a third, but do it right away so they have the maximum amount of time to regrow and set buds. Then, make sure they receive adequate moisture and nutrients for the rest of the summer and do not pinch them. With luck they may bloom again but very late this fall.
Good luck with your mums!
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