Latter part of May to first part of June, before the flowers bloom, is a great time to harvest comfrey, one of the best healing herbs in the planet. The leaves are the most potent in the spring and early summer, so those harvested now are good for drying to use in poultices, infused oils for salves, and fomentations-teas for external use. Gather the leaves midmorning after the dew has dried.
It can be hung in bunches to dry, laid on drying racks (or cookie sheets), put in a paper or onion bag, dried in a dehydrator at about 95 degrees for a few hours, which is what I usually do. You need to make sure that all parts of the plant are exposed to air to prevent mold, so if you are not using a dehydrator, be sure to turn or mix it every day.
When the leaves are completely dry, the easiest way to crumble them is to put them in a food processor and take them for a spin until they are the consistency of tea.
Remove the stalks and place in a glass jar with a tight lid.
Store the jar in a labeled jar in a dark, cool, dry place. It can last up to a year, and then it’s time to do it all again anyway. Any left over comfrey is great in the compost pile for a nutrient boost, and the leaves make excellent fertilizer for your plants as well, so it is never wasted.