That she can sit on. The seat rotates and she can scoot along the box. We have 2-3’ on each side of the box. Ours is 4x 24 at out Utah house

In the other garden we have similar but there are 6 4x8 boxes

The nicest boxes and ones I will do in a next house are made out of 6x6s sacked 3 or 4 high. That is enough to sit on the edges and work

There is a show “growing a greener world” where there is a beautiful garden. You can watch it on Youtube