Comfrey, if you don't know is a herb that is used for making a high potassium tomato feed as well as it being a good compost activator. I believe it's one of the quickest plants to break down or compost. The plant can be cut and used approximately 3 to 4 times a season. The bee's love it's flowers and it grows at an exceptional rate. I think there's a couple of types one that takes over your growing area and the other that has to be divided in order to spread. I make a feed for my potatoes and tomatoes by cutting down a stem or two and breaking them up, and putting them into a five gallon plastic tub with a screw lid filling it with water and leaving it to ferment for three or four weeks. Now this mixture is very strong and needs to be diluted I add a couple if glugs to the watering can and feed the roots rather than the plant. This also has the worst smell ever, rotting dead things is a fair way to describe it.
Try this link:
http://www.permaculture.co.uk/videos/least-12-reasons-plant-comfrey-symphytum-officinale-your-permaculture-garden
