Barefoot Gardener: How Corny!

This small plot of sweet corn in the author’s garden is just starting to produce ears. Photo: J.M. Buck

How to grow your own delicious sweet corn.

Did you know that corn is a man-made vegetable that doesn’t occur naturally in the wild?

Corn is a domesticated form of teosinte, a wild grass found in Mexico in the western Sierra Madre range. It is believed that teosinte was first domesticated around 4,000 to 3,000 B.C. Teosinte was being widely cultivated throughout Mexico by 1400 B.C. Over centuries, teosinte farmers improved breeding techniques and eventually produced maize, a crop that spread across the North American continent and developed into the corn we eat today.

Corn is a warm season crop requiring high temperatures for seed germination and growth. For best germination, soil temperature should be between 70°F and 85°F. If the soil is too cold, the seed won’t sprout.

Dryer lowland areas on the island are especially conducive for corn growing; windward elevations over 2,500 feet prove more challenging for corn cultivation. At 4,000 feet and higher growing corn is very difficult unless you have a solar greenhouse sheltering your garden, and even then success is iffy.

Corn seed tends to rot in very wet conditions, so it is best to cultivate seeds in small pots where temperature and moisture levels can be controlled, preferably indoors in a sunny window or on a seedling heat mat. Once the seedlings are 4 to 5 inches tall, they can be transferred into the ground.

Sweet corn abhors cold weather, and does not tolerate flooding or drought. Additionally, corn is a short-day plant. Some cultivars will not flower when the day is longer than 13 hours, so good harvests are most successful with early spring and late summer plantings.

Corn enjoys a well-drained fluffy loam with a pH of 5.5 to 7.0. Being a heavy feeder, soil fertility is critical to successful growth of sweet corn. It is recommended to add nitrogen to the soil before planting or plant corn in an area where legumes were previously growing.

Sweet corn can become stunted by lack of nutrients, and once it is, it usually doesn’t recover. Adding chicken manure and compost is also a good practice. When transferring new seedlings into the ground, plant at least four rows or more to ensure good pollination. Provide a steady, regular supply of water without saturating the soil or allowing it to become too dry.

Corn is wind-pollinated, so if there is popcorn or livestock feed corn upwind, you want to have a minimum distance of 400 yards between it and your table corn, lest they cross and your corn becomes starchy. Sweet corn varieties can also cross-pollinate between themselves. For instance, if you plant two varieties together, the color of the kernels will change, or both colors can appear on the same cob.

To maintain true cultivars, plant different cultivars at least one month apart and be sure that they have different maturity dates. Fertilize at least once during the growing season with an organic 15-5-8 fertilizer.

An excellent companion planting for corn is alfalfa, as it fixes the nitrogen in the soil. Corn also grows happily alongside vine crops such as cucumbers and muskmelons.

Happy gardening!