saving seeds from garden plants
So, I was wondering about the do's and don'ts of collecting seeds from vegable and fruit plants. I know that plants from of the same type can can cross (like different types of tomatoes for example) but from my understanding so can some plants that don't seem related. How far apart do plants need to be to get "pure" seeds from them. I would love to collect some of my seeds from my flowers and garden plants to use for next year and for trading but don't want a bunch of mixed up stuff. Please help me figure this all out. Thanks!