I remember my DFIL using epsom salts around his tomato plants and they always seem to do really well. I don't think he mixed anything else into though.
I hzc also read where powdered milk was good so a few years back I had some powdered milk that we didn't get around to using and was getting really old in the pantry and that's how we used it, side dressed around the tomato plants. Best I remember it seemed to help and that way the milk didn't go completely to waste!
Maybe I can remember this and try it this year when we plant. Thanks Roses!