Four years ago, I was working at a Garden shop &
greenhouse and I was able to buy 50 tiny starter
plants very cheaply, so I did!
Of course, I ended up giving most of them away because I didn't have room to
plant all of them.
I had five different varities (10 of each) and this is what I found out from the all information provided me and from my experience.
The Chrysanthemums grew best when placed in a sunny location, and they needed to be planted in soil that provides good drainage (so I used pots with Pro-Mix). If they do not get adequate sunlight the
plants tend to get taller and spindly and have weaker stems. They like to be feed with a complete fertilizer (e.g. 5-10-10 or 5-10-5) in the
spring, so I used 5-10-5. I watered them when the soil got dry, especially in the summer when it was hot, but avoided watering them at night because of powdery mildew.
Chrysanthemums will make a bushier
plant if you keep them pinched regularly until about the middle of June for those that are the early bloomers (August), late June for the September bloomers, and early July for the late bloomers (October); for our area (
zone 5) I was told not to pinch them after July 4
(but I pinched some of them as late as mid-July without a problem) or they may not bloom before the first frost. The extreme hot summer temperatures like what we've experienced this summer may cause the blooming to be delayed.
I was told when planting the Chrysanthemums to allow plenty of space between the
plants (usually about 18 - 24") and avoid overcrowding them, so they get plenty of air circulation because they are susceptible to powdery mildew. Mine were in pots so this wasn't an issue.
and gave them to a friend so I could do something different with that bed, but I did take some starts and planted them in pots last year! 
I'm just not wild about their smell!