what causes tomato plant leaves to turn yellow

Question

the top of the plant is nice and green, with fruit,  but the bottom leaves are turning yellow

Answer 1

It could be something as simple as a lack of nitrogen in your soil. If this is the case, you could check the nitrogen level of your soil, or you could just add a little bit of nutritious matter to the soil and watch to see if the yellow tomato leaves don’t just green up for you.

Yellow tomato leaves could be a sign of lack of water. A drip hose is an excellent way to water the soil regularly to help prevent yellow leaves on your tomato plants.

Answer 2

The bottome leaves will fall off and turn yellow as the plant grows. Should be normal.if the rest of the plant is fine. Pluck the bottom ones off that look old, dry or yellow and that should help air flow under the plant and help the plant stay healthy and continue to produce.  

 

If you don;t think that's the answer try more fertilizer might need some nitrogen