The way it was explained to me is that the serious Dahlia growers who show competitively will sometimes grow 20-30 plants of a specific type that they want to show.( searching for the most perfect blooms I guess)
He says it is much easier, and takes up less room, to store just the tuber clumps from the 2-3 best plants, and then take cuttings - 10-15 per tuber clump. Also by only growing from the best and healthiest plants they continually improve their stock.
I have never "shown" and am not really interested in doing that. I also only tend to grow 1-3 of each dahlia that I have, so there isn't much of a reason to take cuttings. I have a friend who does a farmers market flower stand, and she takes lots of early cuttings, and then sells them at the market - they sell much better than tubers to people who are not used to dahlias.
