HUGE Dahlia cluster

tonydahlia

I love my Dahlia's with most of them surviving winters in the soil.
I grew one plant from seed, variety name "Santa Claus". It's been in the ground around three years, but this year it went mad. HUGE plant which took over a small part of the garden and cast a shadow over other plants.
So for the first time I dug it up and it is huge. You can see from the photo it's as big as a mushroom tray.
I washed it down to remove most of the soil, but I am sure more soil could be trapped inside.
I thought I'd have a go at splitting it, but it wont cut down. I thought about pulling off the individual tubers, but is that hurting the plant?
What should I do, and how do I do it?

Teddahlia

I was president of the dahlia club and invited to talk at the garden club. The subject was dividing dahlia clumps. I zipped through a couple of clumps I brought with me. Then one of the garden clump members brought out a clump that looked much like yours. I was thoroughly embarrassed as in real life there is no procedure to divide such a clump except using brute force. People have used axes, splitting mauls, chainsaws, tire irons, machetes and even a band saw, to do the first and second division. You have split it into several pieces with little regard for where the tubers are and assume you will be able to harvest several of the tubers from the "100" that were there. Yes, it is waste of tubers but how many do you need, 25 or 30 and actually 10 would be more than enough for yourself and few friends.