There's quite a few threads about it, but they can be fiddly to find.
squash and peppers These two families are almost guaranteed to cross, and I'd be looking at avoiding cross-pollination through things like barriers or species selection rather than distance.
I'd suggest sticking to one variety of corn unless you have a huge amount of room. It's wind-pollinated and pollen can go for miles.
Corn has another issue to keep in mind.
Many brassica (cabbage family) cross madly; the easiest way I've found with them is to try and stagger flowering.
Beets and chard cross easily and you end up with nothing in particular
Major things I don't worry about: lettuces, tomatoes, beans, herbs.
There's plenty more.
I recommend Suzanne Ashworth's 'Seed to Seed'. It's quite technical and very thorough.
In some of the reviews I read of Seed to Seed they say that most of the book is full of gardening information and only a small amount of actual saving seed information. Is this true in your opinion? I do not need a beginner gardening book. I need the specific details on each species.
"Seed To Seed" is probably the best book on the subject of saving vegetable seeds.
It does give good information regarding safe isolation distances, and techniques.
It is a seed saver's book, NOT a gardening book, though it does give regional information, based on input from successful seed savers from various (US) regions.
I would not consider seed saving without having a copy on hand. An essential tool for seed savers (IMHO).
With corn, if you have the space, (and a long enough growing season), a good alternative is to use varieties with widely spaced pollination times. An extra early variety should not interfere with a late variety.
I know a grower who specializes in peppers. The plants that he reserves for seed saving are isolated in screened cages away from the eating plants. This takes him more time, as he needs to time the opening/closing periods so that the pollinators can get in when they are needed, but not be allowed to visit other varieties of seed plants.
See attached table for guidelines on pepper varieties:
Thank you all, I will be buying the book asap, glad I can trust I am getting the right one. Just from what has been posted on this thread I have a much better understanding of it. Unfortunately all of the squash, watermelon, and pumpkin seeds I have saved this year are no good, as well as the peppers and tomatoes.
Travis Schulert wrote: Unfortunately all of the squash, watermelon, and pumpkin seeds I have saved this year are no good, as well as the peppers and tomatoes.
"No good" as in crossed?
I ask as unless you grew more than one melon species, you're fine: they don't generally cross within the larger cucurbit family.
As far as I know, I've never crossed a tomato. If you mean hybrids, that's a different story.
I'm glad you're getting 'Seed to Seed'. I think it's pretty much the opposite of how you heard it reviewed:
it's extremely detailed on saving seed from specific plant families, to the point of being a bit intimidating for me
They are all open pollinated varieties, but there were 5 squash varieties of various sizes, 5 watermelon varieties, as well as several pumkin varieties... And they were all right next to eachother in the same section of the garden. The tomatoe seed I saved is probably crossed as well because I had a Plum Lemon next to a red roma.