Landrace Gardening: Growing Popcorn

Reader Contribution by Joseph Lofthouse
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Landrace popcorn requires care to preserve and enhance its ability to pop. I imported and planted three popcorns in recent years that had lost their ability to pop well because they had not been maintained in a manner that preserved their popability. In today’s blog I’ll write about my method of selecting for great popping ability. In next week’s blog I’ll write about how to prepare homegrown popcorn for popping.

In the 2009 growing season, I crossed a highly inbred popcorn with a genetically-diverse landrace of non-popping decorative corn. Since that time I have been selecting among the offspring to obtain a genetically-diverse localized landrace of popcorn that tastes great and pops completely. Last week’s post contained a photo showing how well it grows for me.

There are two kinds of starch in popcorn. Clear-looking transparent starch is required for great popping. If the starch is white or milky looking it doesn’t pop well.

Very small kernels don’t produce much volume of popped corn and tend to have a crunchy unpalatable tip. Very large kernels tend to produce old-maids instead of popping. My crossed plants produced many different sizes of kernels. After years of selecting for best popping ability, the kernel size matches very closely to the plain old yellow popcorn sold in the grocery store. They have converged into mid-sized kernels that weigh about 0.18 grams and are about 6 millimeters in diameter.

If the seed coat of the popcorn kernels cracks while drying, then the cracks allow steam to escape so the kernel will not pop. A 20 power jeweler’s loupe can facilitate seeing fine details.

The best popping corn has smooth kernels that form a great pressure chamber to hold the steam inside until it ruptures. Kernels with abrupt edges or that are flat from being squished together form weak pressure chambers that lead to poor popping. This difference is demonstrated in the photo containing two kernels of corn. The kernel on the left has an abrupt edge around the germ, and it is squished flat. Kernels like that don’t pop well. The kernel on the right has a round top, and the germ is imperceptible. Kernels like that pop well. Round kernels (which are called pearl) pop better than pointed kernels (which are called rice).

Considering all those traits of a great popcorn, my method for selecting cobs to plant next year is as follows. If the answer to any question is no then the cob is fed to the chickens.

  • Do the kernels look glassy?
  • Are the kernels about 6 millimeters in diameter?
  • Are the seed coats free of cracks and ruptures?
  • Are the kernels smooth and pearl-shaped?
  • Is the germ imperceptible?

Once a cob has passed all of the above tests, then it is a candidate for test popping. I test each cob in order to determine which pop the best so that I can plant those cobs next year. My method is to take a tablespoon of kernels from one cob, and pop it in a microwave oven in a glass dish. I measure the total volume of popcorn produced, and the number of un-popped kernels. The key to maintaining a great popcorn landrace is that nearly every kernel pops. I write the volume and number of grannies on each cob so that after I have popped every cob I can make decisions about which to plant next year.

Sometimes I write a note on the cob like “easy shelling”, or “great taste.” These are traits that I want to show up more often in my popcorn. If they are associated with poor popping ability, then I might plant them anyway, and detassel them to make a hybrid between plants with great taste and those with great popping ability. Next year I will re-select again. In addition to selecting entire cobs, individual kernels can also be selected that have great shapes.

I was able to take a non-popping decorative corn and turn it into a great popping and great-tasting popcorn by allowing it to promiscuously intercross with popcorn and then selecting among the genetically diverse offspring for great popping ability and glorious flavor. This is part of the reason why I believe that landrace gardening is a path towards food security through common sense and traditional methods.

Next week I’ll write about how to prepare homegrown popcorn for popping.

Joseph Lofthouse grows vegetables in a cold mountain valley where he practices the art of landrace gardening in order to feed his community more effectively.