In the Fall After the flowering season, usually in November cut back to ground level. (After the plant has died back).

After the ground has frozen, mulch the plant well with dried leaves.  This will prevent the plant from suffering damage during freeze and thaw periods throughout the winter.

In the Spring your plant will start emerging from the ground.  At this point the plant should be fertilized. We prefer Fish & Seaweed Emulsion. 
As the plant grows you will want to schedule 1- 2 pinches.  The more you pinch,
 the bushier the plant and the more blooms it will produce. Also, the pinching
controls when the plant will bloom.  If you’re timing your Mum for the Fall ,
the first pinch should be taken by mid-June. The second pinch should not be taken
after mid-July.

Fertilize every 2 weeks throughout the summer.