Yeah, constraining them to ground wouldn't work. I forgot that even cells in the center keep dividing after their initial divide.
I assume you are wanting to do something similar to this?
You say cells can bud two others...are you limiting how many times each cell can divide(like a cell can be a parent to two other cells only?) or was this a simplification of the division of cells? It seems that you will have more than 200 springs for 400 cells unless you are removing them at some point.
If the cells can only be a parent to two child cells, then the initial cell(cell 1) will only be attached to two cells. But, every cell (cells 2, 3, and ...) after that will be attached to three cells. If the cells can be a parent to more than 2 child cells, then there will be n attachments.
You are taking this into account?