We have 3 Big Boy tomatoes and 3 Mountain Magic tomatoes. Before I begin there are a couple of things you need to know: 1) We just found out our soil is nitrogen depleted (not from a home test) and 2)The tomatoes are in 5 gallon buckets. The Mountain Magics seem to be doing fine, considering the soil. The Big Boys are getting gray spots on the bottom and end up rotting completely and this is before they ripen. We did ask someone at our garden center and they think the problem may be due to the extremes from dry to wet but I'm really not sure of that. We do water it every morning since they are in buckets and we've had some really hot days. What is the problem and is it treatable?