Answer: Yellowing leaves on tomato plants can indicate many things from being too dry to being too wet to needing to be fed. Plants in containers usually need to be fed more often because they need watering more often than the same plants in the ground. Try feeding every 2-3 weeks with a half-strength dilution of water soluable fertilizer such as Miracle Gro or Peter's. Sometimes tomato plants drop their lower leaves for no reason at all, and they turn yellow prior to dropping. As long as there are not spots or blotches on the leaves, I don't think there are disease pathogens at work. Be sure to check the undersides of the leaves for signs of aphid feeding. Hope this information helps you determine the cause of the yellowing leaves.
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