I started all of my plants from seeds. The plants are doing great, they are large, bushy, and have healthy leaves. However, my tomatoes, upon getting a bit bigger, are either rotting completely with no warning, or developing black spots on the bottom that eventually tunnel into the fruit. Please help! I am a novice and this is only my third year gardening and I would like to have at least one tomato from my plants! What can I do to stop this. I will provide a picture if necessary so that someone can help me to identify what this is and how to treat it! Thanks ahead of time, I look forward to being a member of this site and learning from all of you!