I just use my own homemade Comfrey tea, and have done for more than 10 years. Not bought any Tomorite et al, since then. Quite frankly I use it on everything that flowers or fruits. It stinks but boy don't the plants just love it! My comfrey patch is quite massive I easily have more plants that I will use, sow I strim a part of the patch, put it on my compost heap, that will quickly grow again, and carry on doing that after I have made 4 large containers of the stuff. My mixture lasts me until the next season. I use a very mild mixture as a general pick me up for plants until they can be put outside. The bees absolutely love flowering comfrey.