Teddahlia Thanks so much for this detailed answer to my questions. I will cull the open centered ones and focus on small tuber pot roots and ask any questions at the next dahlia talk - or if you know of some good articles on pot tubers, I am interested in growing about 30+ varieties and keeping them in the 4" pots if there's a way not to plant those in the ground. (and how to keep them alive in such tiny pots.) I wonder if growing the small tubers point-down is advisable. I tried some of this in the garden last year a la Dick Parshall but didn't take good enough notes on which ones were planted that way. I think everything made tubers, though.
I may be losing this garden space of 14 years (not my land) so I probably should try to make pot tubers of all my favorites, but I'm in a 3 month intensive course and had to go back to gardening work to pay for it in my 70s, so I'm not really functioning that well in the garden! 😄