Corn 101

A few friends have asked me recently for advice about growing corn. Coincidentally, I just harvested all of my corn last week. I've heard (and read) here and there that corn is very easy to grow, but I have to disagree. This is my second year growing corn, and I'm still unsure whether all the work (and space) is worth the pay-off. My attempt at growing corn this year was much more successful than my pitiful attempt last year, so I did want to share a few tidbits I've learned (perhaps the hard way) about growing corn successfully.

First of all, the classic image of corn growing in perfect rows is just wrong. In order for kernels to actually develop, the tassel at the top of the plant must release a yellow powder which falls down and pollinates the silks growing out of each ear of corn. A pretty comical analysis of the evolution of corn can be found in Michael Pollen's Omivore's Dilemma in a segment called "Corn Sex." Basically, the farther apart your corn plants are spaced, the harder it is for the silks to be pollinated. Planting your corn in a grid rather than rows puts the plants closer together and facilitates pollination, giving you more kernels.

I learned this lesson by trial and error. Last year I planted my corn in rows resulting in poor pollination and only about 20% of the kernels actually developing. This year I planted in a block, and when I harvested it, about 90% of the kernels had developed. Much better! If you want to help the pollination along even further, you can manually tap or gently shake the tassels at the top of each stem when you can see the powder drifting down. Just try to keep the pollen on the corn (and off of your hands as much as possible), especially if you have seasonal allergies!

In his book, The Vegetable Gardener's Bible, Ed Smith recommends preparing your site with a few inches of fresh compost and planting your corn seeds or seedlings in blocks, one inch deep and eight inches apart in all directions. Corn is a heavy feeder, he wrote, and should be fertilized often. His book also suggested pole beans as a companion plant, and so I planted two teepees of pole beans directly next to my corn. What happened next surprised me: the corn growing directly next to the green beans took off compared to the plants that were further away from the beans. Hmmmm, that was interesting. I wondered why some of my corn plants looked amazing and others appeared, well, pathetic.

As fate would have it, I stumbled onto an article in Organic Gardening magazine a few days later about Natural Design Gardening. The author discussed the importance of biodiversity in vegetable gardening and farming, and specifically mentioned the Three Sisters concept of inter-planting corn, beans, and squash. In essence, the beans build up or "fix" nitrogen in the soil. The corn feeds off of this natural nitrogen boost from the beans and, in turn, acts as a trellis for the beans to climb. Planting trailing varieties of squash in between the corn and beans provides shade and protection for the corn's shallow root system.

This may be way more scientific information than you want to know, but I'm really encouraging you to try planting this way next season; the results were very impressive! At the end of the season, the corn stalks planted directly next to the beans were literally three feet taller than those that weren't, and the ears of corn were almost twice as large as the others. When I finally pulled up the stalks, the corn that had bordered the beans had a root ball three times wider and deeper than its counterpart further away from the beans.

I am fortunate to teach at a school with a well-funded and supportive PTA and an expansive learning garden with raised beds for every grade level. At the end of the school year my fourth grade students and I planted a Three Sisters garden of corn, beans, and squash in a large raised bed in the kindergarten yard. The bed is set up on a drip system, so it's been watered throughout the summer. I drove by recently and the corn was so tall you could see it from the street, just one month after planting (see photos below). I will be sure to plant my own home garden according to this design next spring.

Back to planting. So, you plant your corn seeds or seedlings in a grid eight inches apart. After the seed has sprouted, I would recommend planting one or two (no more) pole beans seeds about two inches from the corn plant to ensure that the roots intermingle. This will produce stalks of corn so thick and strong that they can withstand a pretty decent gust of wind. However, if you still find your corn sagging to the side, especially when the heavy ears start to fill out, you can go ahead and stake up your corn with bamboo and gardener's tape, or any other stake of your choice. I again learned this lesson the hard way when my corn (the ones further away from the beans, that is) sagged over and onto my next door neighbor's brand new Cadillac SUV (clearly, an urban gardening problem)! You can also prevent corn from falling over by keeping the soil moist but not saturated.

So, let's assume you planted your corn, it's still standing up straight and tall, and the ears are developed... or are they? How do you tell when corn is ready to be harvested? Well, that's tricky and the experts don't necessarily agree. Most gardening books state that corn is ready to harvest when the silks at the end turn brown. Some authors insist you peel open the tip of the cob to check and see if the kernels are pale yellow and there is a milky liquid when a kernel is pricked with a knife or your fingernail. Other authors say you should never open a corn husk before you're going to harvest it because you risk damaging the corn, and the husk should only be opened once the water is boiling on the stove and you're ready to cook it. Instead, these guys recommend that you just "feel" the husk to see if it's full and rounded. Being a visual person, I chose the first method, but I'll leave that up to you.

What I can say is that, once you've decided to bite the bullet and harvest that cob, the one that you've been nurturing and observing and picturing with butter and a little salt all spring and summer long, I hope you don't find what I did inside my corn this year: worms!

That's a blog for another day.