Dividing Helenium...?

[Cosmo and Dibs]

I have a lovely clump of helenium on my allotment, and I'd love to divide it and take half of it home.

I know that spring is the best time to do this.

However, I tried to do so in spring but it was far too tough to dig up or get a spade through.

How should I be doing it?

Or should I just propagate from seed? Is this practical?

[Two_Sheds]

is this any help? Propagating and growing Heleniums