Saving seeds from tomatoes is really easy and kind of fun. The process of how to save tomato seeds for next year is not very complicated, but it does involve a couple of steps. Why would you want to save tomato seeds when you can buy tomato plant starts and tomatoes at the local grocery store and farmers market? Simple, really. When you save seeds from a tomato you have grown, you are helping preserve the genetic diversity of tomatoes, and selecting for characteristics that make a tomato better. To save tomato seeds all you need is an heirloom tomato, a container, a jar in this case, and a few days.