I heard recently that a good way to tell if your tomato needs water is this: Touch your tomato leaves, and if they are damp, don't water, and if they are not damp, water them.

Is this true or false?

Also, leaves on the bottom of a few of the plants are turning yellow- too much water?

I am growing these particular plants in 5 gallon white plastic grow bags with miracle grow moisture control mix. They have blossoms and some have fruit. It's been in the high 80's- low 90's and hasn't rained for ages. I water about 2x a week.