Last weekend I thought I had got a bargain when I bought a dahlia tuber for 99p from a supermarket. However, when I got it home most of the bits of the tuber had fallen off and only one very small part had any roots attached. Will the individual bits grow? I have potted them 3" deep into a pot. Was this the right thing to do?
Probably not, you need part of the crown of the tuber ie. where the stem meets the tuber, this is where the new growth will form