Hi Susie,
Yes we can leave them in the ground, mostly. Maybe 20% of the time we get casualties. Perhaps we get too much rain, so I am planning to bury the tubers three inches deeper ( by putting three inches more soil/compost on top), and then putting plastic pot bases on top.
However I am now beginning to think that the mother tuber rots after one or two years, and may need to be separated. Sometimes when I dig tubers out they split and disintegrate, and it is mostly around the mother tuber.
It may be that the natural development of dahlias is for the center tuber to rot, and the descendent tubers to move out from that location to form their own clumps.
Peter
