Sounds like the plant is under some sort of stress.

Knowing where you are located or at least your gardening zone would be a big help in answering your question. The possible causes are many and could simply be planting too late.

Over-fertilizing is another option given the info provided as it can lead to large plants with small/low fruit production.

Are your plants heavily mulched as they should be? Do you water deeply or are you one of the 20 mins. a day type water folks? Raised mounds dry out quickly and so need lots of deep watering and heavy mulching.

Have you ever had your soil tested to see what it lacks? Miracle Grow lacks many nutrients.

Need much more information.

Dave

Sorry for not providing my zone since it makes a big difference. The soil has been analyzed by the university and there were no recommended enhancements for growing tomatoes. The plants are mulched because of the problem with silt and absorption. Also I confess to being one of those 20 minute persons, but I am only tending 12 plants. The garden area is quite flat, so since I have never delt with a silt garden I probably miss judge the water volume requirements. I plan to bring in as much compost as possible to work in this fall, but I will try to find a way to get more water to these plants in the meantime.