From the Mailbag: Do I need to isolate open-pollinated corn?

September 4 - Bob D. writes to ask:

"I have two questions about corn. Can you plant two different kinds of heritage corn in the same small garden? Can you stagger a planting of heritage corn for a longer picking?"

If you're not planning to save the seed, then yes you can plant two different heritage/open-pollinated varieties next to each other. And yes, you can stagger the plantings for a longer picking - this works for both open-pollinated and hybrid corn (I do it all the time).

If you want to save seed for planting in the future, then you need to either isolate by space (I think 75-100 feet is considered adequate), isolate by time (stagger the plantings so the silk is drying down on one variety before the tassels come up on the other), or plant in alternate years. Corn seed should be good for at least three years in my experience, as long as you keep it cool and dry.

With hybrid corn, there is one case where you want to isolate varieties - even if you'll just be eating it. All "supersweet" (sh₂) varieties must be grown apart from non-supersweet varieties, using any of the methods listed in the previous paragraph - note that 25 feet is probably fine in this case. Supersweet kernels that are pollinated with non-supersweet pollen will often become tough and unpalatable.