Growing Sweet Corn In A Cool Climate
Who doesn’t love sweet corn? Crunchy, tender, sweet and earthy, corn tastes as good raw as cooked and belongs in dozens of splendid recipes. However, growing corn can be a challenge when you live where nights are cool. Since soil temperatures closely follow night air temperatures, corn planting should be delayed until garden soil is as warm as baby’s bath water.
Sadly, that may never happen all summer, so we usually need to give corn a bit of help if we want a decent harvest. (We also need to beat the raccoons to the crop, but that’s another story.) For fabulous sweet corn, plant in full sun and warm, well drained soil (above 60 degrees F is best for this heat-loving crop). To build rich corn flavor, amend soil generously with mature compost and mulch plants deeply. To boost soil heat, cover soil with sheets of red plastic (which is supposed to increase crop yields), spreading it out between the rows.
Let The Wind Blow
If early summer is cool, plant corn indoors under lights, transplanting gently when starts are 4-5 inches tall. Otherwise, plant seed corn an inch deep and about 12-18 inches apart. Since corn is wind pollinated, plant corn in 4 x 4 foot blocks to encourage good pollination. To avoid cross-pollination between corn varieties, separate various kinds by about 500 feet. Those with small gardens can enjoy more variety by corn-sharing with neighbors, each family growing a different kind, then sharing the ears when they ripen.
Fishy Growing Tips
Water corn weekly, providing about an inch of water each time. Mulch will help conserve soil moisture, but in hot weather, you may need to water more often to keep ears full. Fertilize every few weeks with a mild (5-5-5) organic fertilizer as well as some kelp meal. Back in the day, native people planted each hill of corn with a fat fish to provide a steady source of nutrients, and if you have lots of dead fish lying around, that still works. Otherwise, add fish emulsion or meal when you plant. Mulch generously with compost, which feeds the soil, enhances natural flavors by boosting sugar content, and also help to keep weeds from sprouting. If your garden space is small, consider growing traditional “three sisters” companion crops of beans and squash, as native American people have forever.
Dents and Flints and Cow Corn
There are quite a few types of corn, from field corn and popcorn to ultrasweet hybrid corn. I vividly recall eating an ear (OK, one bite) of almost woody corn that turned out to be dent or “cow corn.” No thanks. However, dent corn (Zea mays indenata) is delicious ground, and some, like multicolored Earthtones, are utterly beautiful ornamentals, with gently tinted kernels in shades of gold, copper, bronze, pink, rose, green and yellow.
Native Americans have grown flint corn for millenia and flavorful heritage types can still be found in seed catalogs. These days, this very hard (flint-like) Indian corn (Zea mays indurata) is mostly used for hominy and grits in the US, though it is still widely grown throughout South and Central America. Though once a staple, flour corn (Zea mays amylacea) is rarely grown in home gardens today. White or blue, flour corn is mainly used in tortillas and baked goods.
Corn For Popping
Popcorn is Zea mays everta (everta means inside out), a flint-type corn with a soft center and a very hard hull that turns out to be an excellent source of antioxidant polyphenols. Popcorn pops when the soft center steams enough to blow itself open. Archeological digs in New Mexico show that people have been enjoying popcorn since at least 3600 B.C. so no wonder we still love the stuff!
How Sweet It Is
Whether yellow, white, or a blend of both (bicolor), sweet corns are hybridized to produce tender, extra-sweet kernels. While field corn runs about 4% sugars, sweet corns may be 10% or more, at least when fresh. Sadly, corn sugars start to convert to starches as soon as the ear is picked and can lost half its sweetness in a day. As I mentioned in my last post, instead of growing GMO corn, choose from a lovely range of delectable varieties such as Precocious, an early yellow corn with plump, buttery kernels. Next comes Bodacious, another sweet yellow with big ears great for eating on the cob. Honey Select is a delectable super sweet yellow corn, while Jubilee is excellent for canning or freezing.
If you prefer bicolors, try Delectable, with intensely sweet gold and white kernels on generous ears, or Sugar Dots, a new classic and a reliable cropper. Sugar Pearl offers meltingly sweet, creamy white kernels, while brilliantly burgundy Double Red Sweet combines lovely flavor with stunning beauty on the plate.
I’ve never had enough room or sun to grow corn before but this year I have a new community garden plot and was interested in giving it a try. Thanks for all this great, and timely advice!
Glad to be of help, and I hope your corn thrives in this cool summer!