The tomatoes, generally, not a problem -- tomatoes are overwhelmingly self-pollinated. You might get the rare cross, but not very often.

Corn is a different story, however. It has windblown pollen which goes far and wide. And, since the part used for food, the kernel, IS the next generation, any cross-pollination shows up right away. Some cross-pollination, for example, when Sh2 hybrids and SE hybrids cross, can result in very tough kernels. It's best to try to seperate corn either by distance, 50 feet at a minimum, or by time, 2 weeks between maturity dates.

Go to the link below and then look for Blueflint's comments on maintaining purity of corn. I have also had significant crossing between tomatoes when grown side by side. But by planting a couple plants of the same variety, in blocks, and with at least 15' isolation between them, I haven't had any crosses now, in years.

George

Thank you for your information. Do you think that if I have a large shed between the hybrid and the heirloom corn there will still be cross pollination?

That's certainly a good help in seperating them. I'd also seperate them by maturity date as mentioned above. Are the both the same dtm? If so plant one 2 weeks earlier. If they are different say 80dtm and 95dtm then no problem planting together. I wish I had room for more than one type of corn. I love corn, and there's so many varieties I'd love to try. I'm only going w/ 36 plants of ruby queen se.

Here is a link that might be useful: a very small example of dtm

Ok here is what I got. Early sunglow Hybrid (harvest in 63 days) planted March 1st and Golden Cross Bantam Heirloom (harvest in 80 days) planted March 6.

Sounds absolutely fine. I wish I could plant mine that early, I might get two crops.