where mums go to die

Actual crime scene photo

I grow lots of flowers. Lots. Hard flowers, like roses. The roses are huge and flourishing.  My marigolds are the biggest in the block, my tulips the first to show in the spring. I grow six types of herbs in my kitchen window. Other than the pumpkins (which were murdered by maurauding beetles) my garden did quite well and is still producing tomatoes, carrots and peppers. I am good at plants. Except for mums. This is the second mum I have killed this season. Mums are easy. Anyone can keep a mum alive. Not me. Good grief, they're only meant to last for a couple of months anyway. What am I doing wrong? I am anathema to chrysanthemums. So weird.