Flowers in bloom in September - zone 5?

I am getting married in September 2011. To save some money, my parents have decided to try to grow some of the flowers that we will use for the wedding (I'm hoping to get my future in laws involved too). We live in upstate, NY (Saratoga/Albany area). I know nothing about flowers. Could anyone suggest some different kinds that are in bloom in September in my area? Thanks for the help!