Comfrey is ideal for making a powerful liquid feed as it contains the 3 vital elements, Nitrogen, Potassium and Phosphorous that are essential for healthy plant growth.
Very accurate with it's description of a "cut and come again" had it growing all summer and added a different style of lettuce to my salads. I found it to have a slight peppery taste, similar in taste to the land/American cress I have.