Last spring I purchased some canna rizomes from a reputable local nursery, I believe they were Van Bloem stock, also reputable. I followed the instructions on the package, didn't overwater, waiting until sprouts appeared. To my dismay only six of the twelve that I planted germinated, and only one survived. I attempted to start them in my greenhouse in May. Temperatures ranged from +10C to +30C daily, at least 8 hrs direct sunlight. Started in soil less mix, any ideas, suggestions will be appreciated.I know that I must have done something wrong, because everything I read indicates that cannas are easy to grow.

I dug up the surviving canna in the fall after the first frost, potted it and placed it in an area of my home with a large east facing window and south facing window and it's doing quite well, almost 2 feet tall and very healthy.