Need more info. What kind of tomatoes? Are there flowers but not on trusses, or no flowers at all? Fruit/no fruit? And, of course, roughly where are you? Are you pruning? Easy to mistakenly prune a truss.

If few flowers, you may be dealing with an over nitrogenated soil. Nitrogen encourages foliage development, but not fruiting.

Agree with Dan that much more info is needed. A photo would also help and so would your location info. Are these in containers or in the ground? What and how often have you fed them?

Dave

I think you may have answered my question Dan. I fed with some chicken pellets when they were small,the first time I have done this. It did ocure to me but you have confirmed my fear. D'oh. Anything I can do?

So they are growing indoors, very leggy due to insufficient light and possibly over warm conditions, in very small containers and pruned to a single stem. All those conditions alone would explain your current problems. Add in the chicken pellets and you'll get very few blooms.

Bloom trusses develop on stems approx. every 2-3 leaf nodes only. Your leaf nodes are so stretched, so long and with only 1 stem you'll only get a couple of trusses.

Dave

The pots seem to be about 5 gallon but not fully utilized. Not ideal but can be managed. I would fill them almost up to the rim. Then a secondary root system may grow to give the plants more vigor .

Sey