All the lower leaves on my tomato plants started turning yellow, and spotted. When the tomatoes started coming in the bottoms are rotted. What causes this? Thanks.
That sounds like blossom-end rot. There's a lot of information out there about this including on this site, but basically, it's caused by lack of calcium. This is caused by inconsistent soil moisture and too much soil nitrogen (use tomato fertilizer high in phosphate instead). If the soil is bare dry grass clippings or other organic mulches spread around the plant can improve moisture stability.
