Rhubarb crown size

That is probably quite a young root. They go up to about a yard across.

13 crowns should supply you and your neighbours with more than enough rhubarb and you will probably want to dig some of the crowns up to make space for other crops.

Observe the crowns this year. If you are lucky there are some early and some late varieties. See which are vigorous and which are weak. Decide which you want to keep.

When you do divide them keep all the outside bit's and discard the middle.