I have seen a couple folk here state that 'first year' tubers don't provide strong plants, or don't bloom until late, and I'm wondering where that is coming from.

Any tuber you purchase is technically a 'first year tuber,' a product of the prior season's plant.

The 'mother tuber' (last year's starter tuber) is rarely kept, as most the energy is sapped out of it, and often rot in storage.

Perhaps you feel that the mother tuber needs to be 'acclimated' to your soil or zone before producing tubers that will perform well?

I have grown many, many tubers sent from all over the lower 48, and have not experienced any adjustment period needed. Growers that receive tubers from a different growing cycle like Australia to the US often talk about a lag in performance, but I haven't heard of it otherwise in dahlia grower circles.

If you're not talking about the theory of soil acclimation, please explain to me, because I'm missing something in your logic. :-)