This is my second year growing popcorn. Last year I grew a miniature variety which I harvested in early August. While the variety matured on the early side, I think I was a little premature in harvesting last year. The popcorn popped. But the kernels were smaller than even the miniature variety would necessarily have produced.
I get a surprising amount of traffic to my blog on search terms for harvesting popcorn. So it seems a lot of home growers out there are looking for information on when to harvest their crop. Who knew? Harvesting sweet corn can be done simply by counting three weeks from when the tassels appear. But popcorn harvest is much more ambiguous. I myself have been a little uncertain this year.
So, plucky soul that I am, I got my question to someone at the Rodale Institute, which is reasonably local to me. The word that came back was that, ideally, ears of popcorn should dry on the stalk. However, if the weather continues wet, it may be better to harvest the popcorn and dry it inside. Ears ready for harvest will have lost their green coloration and the husks will look dry. One indicator that will tell you harvest should have been done yesterday is the stalk. If the stalk looks dry, but becomes soft and pithy, the plant is essentially rotting, and that's eventually going to affect the ear of corn too. If you see those characteristics on your popcorn stalks, harvest the ears and get them out of the damp. Above all, the gardener should prevent the ear of corn getting moldy. Admittedly, harvesting popcorn calls for subjective judgment and a close eye on the weather forecast. There's no rule based on a fixed number of days after planting, or a hard and fast date on the calendar. That's the way it goes with some crops.
Drying the corn inside can be done on screens, such as those from old storm doors, or on wire fencing or hardware cloth that you might use in the garden. You could also put the ears into net bags saved from store-bought onions, and then hang the bags up air out. If you have burlap bags, that might also work. Hanging the popcorn up will also discourage any critters you might have in a garage or outdoor drying area from helping themselves. It's best to dry the corn, like just about everything else, out of direct sunlight, away from intense heat, but where there's lots of air circulation.
There's still a bit of green on this mostly dried out husk. If the weather cooperates and stays dry, I'll let the green fade completely before harvesting.
Given these guidelines, I'm going to let my popcorn go for a while yet, if I can. We had several days of very wet weather last week, but this week has turned autumnal and dry. I'm hoping our current pattern of just warm, dry days and cool nights will hold. If it does, I may be able to harvest in a couple weeks.
P.S. If you want suggestions on cooking perfect oil-popped popcorn, go here.