I've been thinking about doing this for a long time but I know it stinks really bad so have been procrastinating on it. I'm not sure if you said, but how long do you let it sit in the buckets before you start using it?
I try a version of this with my garden clippings/purnings, the old timers down here in the south swear that it’s the best fertilizer you can get. I’ve never grown comfrey, I will have it try it.