They may need more nitrogen which makes them green and lush. Also too much or too little water can cause this. You would know the answer to that one.
Probably from lack of phosphate and calcium. Are they getting enough water and a good 13-13-13 fertilizer would do wonders for them...Full sun I hope.
My tomato plants are turning yellow from the top center down. Why? I put miracle grow on them about a week ago according to package instructions. Not all varieties I planted so far are yellow, just the Roma, and Grape .
My stems to my flower is turning yellow on my tomato plant why