Please pardon me while I indulge in a blog post all about my recent obsession with Glass Gem corn. I was enchanted by photos of its shining, colorful kernels when they first made the rounds in 2012, but never seriously considered growing it until this year. And even that was a very last-minute decision–when I saw yet another online article referencing this unusual heirloom back in early May, I immediately went online and ordered a single seed packet from Native Seeds/SEARCH to sow as soon as possible. I’ve grown a lot of different heirlooms over the past six seasons, but this one has really swept me off my feet with its unique beauty.
What is Glass Gem Corn?
Glass Gem corn is an heirloom flint corn variety recently introduced to the public by Native Seeds/SEARCH, a non-profit conservation organization based in Tuscon, Arizona. For over 30 years, the organization has been collecting, preserving, and distributing heirloom vegetable varieties that have played an important role in agriculture in the Southwestern United States.
The full history of Glass Gem corn can be found on the Native Seeds/SEARCH blog, but the Cliff Notes version is that Glass Gem was carefully grown and stewarded for many years by Carl Barnes, a part-Cherokee farmer from Oklahoma. In 2010, Barnes was nearing the end of his gardening career and decided to pass on his seed collection to his protégé, Greg Schoen. Schoen in turn passed some of the seeds along to Bill McDorman, who would later become the executive director of Native Seeds/SEARCH. McDorman was intrigued by the name Glass Gem and decided to grow some of it in his own garden. Naturally, he was just as taken by the results as the rest of us have been, and decided to introduce it to a wider audience.
What is Flint Corn?
There are three basic types of grain corn: flint, flour, and dent. Unlike sweet corn, grain corns are dried before processing rather than eaten fresh. Dent corn is a recent invention, dating back to the mid-1800s, and most of the corn now grown in the United States is of this type. It’s used for everything from tortilla chips to high fructose corn syrup to plastics. Flint and flour corn, on the other hand, were the types historically used as staple crops by Native Americans and adopted by early Americans.
Glass Gem is a flint corn variety. A corn kernel is composed of four primary parts: the pericarp, the aleurone, the endosperm, and the germ. The pericarp and aleurone are two thin outer layers which surround the endosperm and germ, and are where any colorful pigments reside. The endosperm is a large part of the kernel interior. In flint corns, the endosperm is primarily hard, or flinty, and is either white or yellow. So when flint corns are ground down or popped, they are primarily white or yellow, though some flecks of color from the pericarp and aleurone can remain in the meal. (Kind of like how red okra turns green when you cook it.)
Because the endosperm is so hard in flint corn, the kernels are tough and there will always be some grittiness in the resulting meal, no matter how finely ground. Flint corns are suitable for making into grits and cornmeal, and some can also be used as popcorn. (For a fine flour suitable for bread and cakes, flour corn is the way to go.)
So being a flint corn, Glass Gem corn can’t be eaten fresh like sweet corn. But it can be dried and ground into grits or meal, popped as popcorn, or simply used as decoration.
My Experience with Glass Gem Corn
As I mentioned above, I purchased my seeds a little later that I would like, but was able to get them in the ground on May 20th. I didn’t write down the exact number, but I recall that there were either 52 or 54 seeds total. Because I was working with a raised bed that was 32″ wide, I planted the rows really a little too close at only 8-9″ apart. The plants themselves were too close as well, at 6-7″. With relatively few seeds, I was worried about adequate pollination. I had originally planned on thinning the plants once they germinated, but couldn’t quite bring myself to do it when the time came. This turned out to be a bit of a problem later on, as air circulation between plants was poor.
The seeds had germinated and were putting on their first true leaves by May 25th. Corn is a heavy feeder, so I fertilized it several times over the summer with organic hydrolyzed fish fertilizer. Because I had such a small block of plants, I mulched between the plants with shredded cardboard and never had to weed them afterwards due to the mulch and the shade from the stalks. The plants grew rapidly at first, and then stalled out for a little while in late June.
When they started growing again, they did so rapidly. By mid-July I was getting worried because I was starting to see tassel development but no ears emerging. By the time the tassels were in full flower on July 22nd, however, there were plenty of little nascent ears with silks ready for pollination.
It was interesting to watch the veritable swarm of pollinators on the corn in late July. Bumblebees were most prominent, but there were a number of other native bees as well, and even a few honeybees. I could see the grains of pollen trickling down to the ears below as the industrious bees jostled the tassels. Between the breeze and the bees dislodging pollen, I got pretty good pollination on most of the ears.
This was my first time growing flint corn, so I was a little uncertain about harvesting. I checked in on the ears as they were developing and they seemed so thin that I was worried they hadn’t been properly pollinated. Upon harvesting I discovered that a lot of the ears are just naturally slim, and not nearly as thick as sweet corn, which is what I’m used to growing.
In the first half of August I noticed ants hanging around the tips of some of the ears. Though I couldn’t see it at the time because they were concealed by some of the husks, the ants were farming aphids on the corn. I’d read ahead of time that corn earworms were mostly a problem with sweet corn, not flint corn. But when I harvested the corn, many of the ears were damaged at the tips, as with earworms. I never once found an earworm, on any of the ears, but next year I think I’ll take precautions anyway.
Quite a few ears had molded around the site of the damage and I had to discard them. I imagine this was due to a combination of the aforementioned poor air circulation, the high humidity, and the pest damage. I think I learned my lesson on plant spacing!
I started harvesting the corn on August 28th, and harvested small batches over the next few days until I had gathered all the formed ears. There were a few ears that developed too late to be pollinated, but overall the harvested ears were well-developed. Peeling the husks back to reveal the colors within was an exciting process, a little like opening presents on Christmas morning. Some of the ears were just breathtaking, and I got a good variety of colors from the single packet.
After harvesting, I trimmed the damaged ears, which resulted in a few really short and stubby ears. I don’t have a good place to hang the ears indoors so right now they’re spread out in a single layer on wire shelves for air circulation.
Since this year’s harvest was small, my two primary purposes are to save seed for next year and to use a few of the nicest ears as decoration. Beyond that, I hope to have enough to try grinding some and popping some. I think it’s safe to say that I’ve caught the flint corn bug. This winter I plan to revisit the section on flint and flour corns in Carol Deppe’s excellent book, The Resilient Gardener, and plan for an actual corn patch next year.
Have you ever grown flint corn? What was your experience?