It sounds as if they are way too shallow to grow full-sized tomato plants. Do you mean that there are no drainage holes?

It would probably be a good idea to transplant these tomatoes into the biggest containers that you can find and give them some fertilizer.

The container that you have would be better for growing something short like lettuce, and It would need drainage holes.

Linda

Sounds like you are over-watering. In a properly sized container watering every day shouldn't be needed. Especially if there are no drainage holes as that allows the soil at the root level to stay wet and soggy all the time and the roots rot. Plus 6" in height is way too shallow for tomato plants.

Dave

Actually, I have never used pots for planting tomatoes. Its that my landlord does not let me use any part of the garden. may be he is too mean. I am going to transfer the plants to new pots. buckets will be good I guess and this time I will make holes in the pots. Thank you all for your suggestions. I will post again with the progress of my work.