I have the exact same problem. In my outdoor garden I cut back on the water to make the plants produce more fruit, but how do you cut back on the water in a hydroponic garden?

what are you feeding them with?

The liquid plant food that came with the hydroponic garden. I planted the seeds around Thanksgiving. The stocks grow all the way up to the LED lights, but there are none of those yellow things that the tomatoes grow out of.

lol, thats not a lot to go on ;) How old are your plants? most toms need to be at least 2 months old before they`ll flower. Temperature also plays a part, but if they are indoors i guess they should be staying above 60F. The other variable is light intensity and duration. Toms are a high light plant (full sun) and will tend to stay in vegetative growth if they`re not receiving enough.

Just looked up what date Thanksgiving was..24th November so its possible they just need a bit more time to mature. The flower heads are easy to spot, basically look for small furry pods in the lowest truss if its an indeterminate (vine) variety or anywhere on the plant if its a determinate (bush) variety.

The temperature's been in the 30's and 40's much of the time, so perhaps that's the reason. I'll give them more time. Thanks!

thats way too cold, some frost protection might not go amiss. The ideal temperature for toms is 78F in the day and 64F at night ;)

I had the same problem last year when i put my tomatoes in a west facing conservatory, loads of growth only 4 toms, leaves the same as yours, I think the problem was lack of light the toms just kept growing and I should have stopped the at 5th truss. Could have been too late in feeding bloom feed. Thinking on this the conservatory may not have been ventilated enough to let in fertilising insects as well.