Cut back the stems to a few inches off the ground and dig up the tubers. Hang them upside down in a frost-free place for a few days, to help dry them out. Store them in trays of dry compost for the winter. In mild areas, you can risk leaving them in the ground.
I've no idea MWB. I'd imagine so, if they were mulched, otherwise it would've been a waste of time. Pentalpha's right though. You should cut them down, leaving the stems, but we have a gardener, so I'm not sure what he did with the things. I love the flowers, but don't get too near them in bloom because they seem to get full of earwigs! Eeeew!! x
You put your tuber in a pot with the old stems just above the surface of the compost .This should then produce shoots. You can then cut pieces which have a shoot from the tuber You can then pot these shoots up ,grow them on and put the old tuber back in the ground .
I wonder why our man mulched them then? Would the same ones've appeared? I'm sorry - I've no idea, but I DO know that's what he did. : (
Maybe he was trying to kill them off!!!! NOT such a joke, considering that I won't have the flowers in the house...because of the earwigs.
People are very divided on dahlias .Some say leave them in the ground say some say dig them up and store them .If you are growing them for show then I would dig them up ,store and divide rather than risk heavy frost and rain which can just cause them to rot in the ground .
As for earwigs if you support them with canes then if you put a little plastic flowerpot upside down on top of the canes the earwigs will hide in there and can be got rid of. Preferably at arms length .
What a fantastic fountain of knowledge you are! Thank you very much. I'll have to ask our man if he does this anyway. He's of the old school, and should know these things. Cheers.