Generally the first half of May is the ideal planting time for corn in the midwest. As far north as you are, you will probably want to go with a 90-100 day variety. Talk to a local seed company. Tell them you want something for a wildlife food plot, and would prefer something with good standability and stalk strength, and medium plant height. The high performance hybrids farmers normally use have tall spindley stalks that won't stay standing late into hunting season like what you're looking for.