GP— that sounds like s good technique, and the proof of its validity is your success. That is interesting to read about. BTW, you understand that I was talking about propagating comfrey, not toms, right? Oké Cayu, that is safe then. Do choose your planting site carefully, for the comfrey will be there a long time. If you have a little sunny place at home that would be perhaps the best in the sense that when you leave or change plots at the muni-gardens that you will not be leaving someone else to deal with your comfrey.
I have heard about putting an egg under each plant, never tried it. We dry egg shells, crush them and scatter some into the hole and some around the plant.
Every time I've had a problem with BER it was due to inconsistent watering. Never let your plants go completely dry. Many of my toms are in containers so they are fall pry to my neglect, so if they every wilt, all the fruit that is set will have that leathery bottom. Then I kick myself for forgetting. (But I always add a handful of Epsom salts to the planting hole.)