I've read how people grow tomatoes for seed companies and would have plots of land away from other gardens to prevent cross pollination. I began to think of my tomato seeds, which I save. I grow heritage tomatoes, some I buy, some are given to me and occasionally I find tomatoes I like and save those seeds as well. Since my garden is a suburban lot and lots of other gardens around ,there is stuff drifting around. I'll plant few tomatoes of one variety, few more of another and so on. I'll leave fruit of each variety to ripen and save seeds. I wonder now how pure are these tomato seeds, grown in close proximity.