|The magic ingredients|
1 part bone mealJust mix all the ingredients and you are all set.
1 part cornmeal
1/2 part powdered milk
1/4 part Epsom salt
The bone meal is a source of phosphorous, which is good for root development. The cornmeal is supposed to act as an anti-fungal agent. Powdered milk supposedly ups the calcium content of the soil, which might help with blossom end rot (though BER is really more about inconsistent watering than low levels of calcium in the soil). Epsom salts add magnesium.
At planting time you throw a handful (maybe around 1/2 a cup) of Mumsey's mix into the planting hole. Make sure you mix it into the loose dirt (i.e. don't plant the tomato on top of a pile of Mumsey's Mix). Then plant your tomatoes as usual. Some folks side dress with another handful about 6 weeks after planting. Because I sheet mulch I'm not doing that.
There are legions of people on various forums who swear by this stuff. I am crossing my fingers that I have healthier plants this year. Maybe this will help.
Any other additions that you swear by?