If I plant Hierloom and Hybrid tomatos side by side will they cross pollinate. There for making the seed saved from the Hierloom no longer a hierloom.

I just read the section on tomatoes in [u]Seed to Seed[/u] by Suzanne Ashworth, pg 151-155. It states that most cultivated varieties are self polinating and cross polination is not a problem. To be safe, you may want to isolate a few flowers in a paper bag, and polinate by hand to gaurantee the purity of the seeds.

It depends on the heirloom. Tomatoes are self pollinators butThe potato leafed varieties will cross pollinate much more easliy than the narrower leaved types.

If you are saving a type for seed isolate it by at least 24 feet from all other types and plant at least 8 plants of that type you are saving seed from to ensure good genetic diversity. It is best to plant the plants in a block.

Realize that in an organic garden there are something like 500 times the pollinators that there are in a garden that gets sprayed with poisons so the liklihood of cross pollination in an organic garden is much much higher than a conventional gardenso I would advise tripling isolation spacing. I believe the USDA says to keep tomatoes 8' apart but I would say 24' is a bare minimum unless you are covering the plants with something like tuf bel (and expensive row cover that is perfect for seed breeding) or have some other way of isolating the plants.