Harvesting Marshmallow

I have just this year started to dabble with growing some of my own medicinal herbs and was wondering how I would go about harvesting my marshmallow plant. It seems to be growing extremely well in my garden, but I am unsure as to what parts of the plants I should be thinking about using for the medicinal value. Any advice you could give would be appreciated.

The marshmallow root is the part used medicinally. Pull or dig the roots in the fall after the frosts have hit. Generally, with most root crops the potency increases in the fall when plants store resources in the roots for the winter. In southern Ontario, late September to mid October is ideal.
Wash the roots, cut or slice (or not if the roots are small), and dry on a screen in a well ventilated area, protected from the sun. Cutting or slicing the roots helps them to dry quicker, which is a good thing. Heat up to 30-35 degrees Celsius is helpful, but be careful to keep the temperature below 40 degrees Celsius. Roots are dry when they become hard and brittle and are no longer "leathery".