Sweet corn "isolation required"

[Jstpssng]

When we had corn it was never isolated. We had a "corn patch" about 40' x 80'. Always planted three types of sweet corn. Three different germination/picking dates. That way we had corn for a longer time.

It never seemed to make any difference. Each variety was easily identifiable and remained true to its type.

One year we planted a new, ultra productive corn type. About a week before picking the blackbirds came in and ate it all.

They probably rushed it so that they could beat the raccoons and skunks. Also the crows, turkeys, squirrels...

 

[LouNY]

Your corns growing days are not calendar days.

Corn growing degree days (GDD) are calculated by subtracting the plant's lower base or threshold temperature of 50 °F (10 °C) from the average daily air temperature in °F or °C. Average daily air temperature is calculated by averaging the daily maximum and minimum air temperatures measured in any 24-hour period.

NDAWN Corn Growing Degree Days Information

If you bunch your different varieties together, planting the same seeds in a cluster of shorter rows you will get better germination then say 2 long rows of the same corn. As far as them cross pollinating it will not make a difference to the eating corn.
If you are trying to save seed from the corn that you raised it would, but most sweet corn is hybrids what you raise quite likely will not be what you planted.
If that is the intent you will need one of the "heirloom" breeds and it would need to be completely isolated.