With mallow, I do not separate roots from leaves, but store the dried and ground product all together, labelled “whole mallow.”. As for fresh, if the root is really thick, I chop it up into tiny pieces before drying, then grind it up after it is dry. Thin stringy roots i just dry whole.
I suppose I could grind up the fresh stuff in the food processor, then spread it on a sheet of parchment or paper plate to dry, then grind it up further once dry, but I’m too lazy to do that.
I guess it would be different if I were processing larger quantities, but at this point it’s only enough for me and a few close family members.