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How to grow a great crop of sweet corn

In the Garden

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It is pretty much a “given” that fresh sweet corn is delicious, and if cared for correctly, it can be a relatively easy crop to grow.

Sweet corn is a warm-season crop that will germinate best when the soil temperature is above 55 degrees Fahrenheit. Corn is actually a type of grass that was domesticated and developed for human consumption.

Sweet corn should be planted with plenty of room to grow, will not be crowded, and not be shaded by other plants or buildings. Plant your sweet corn in blocks with short rows rather than long single, or double rows. The reason is that corn is wind pollinated and planting in a block allows the corn pollen to stay within the group of plants better and pollinate the ears more efficiently.

If you plant in long rows that are only two or three rows thick, you will more than likely have ears that are only half-developed due to the pollen being blown away from the ears as it falls from the tops of the plants.

Plant your seeds one inch deep and at least eight inches apart. Many times gardeners will plant them 12 inches apart to ensure adequate sunlight for each plant. Your corn rows should have at least 2 ½ to 3 feet between them for sufficient growing space and sunlight.

Many home gardeners make the mistake of overplanting their corn and, instead of getting lots of large ears of corn, they get tall spindly plants that have none or just a few small undeveloped ears. It can be easy to think when planting that you need to plant more than recommended since the seeds are small and it takes up such a large space, but giving plenty of room to your plants is critical for good production.

Do not fluctuate your watering schedule on corn as it needs consistent, season-long water availability. It constantly needs water for some aspect of its lifecycle — whether it’s sprouting, stalk growth and leaf development, or the kernels swelling and filling—having consistent watering is crucial.

An irrigating mistake during any of these stages can lead to stunting and poor production. Corn is a heavy feeder of nitrogen and requires sufficient amounts of the other major nutrients for good health and development. Dependent upon your soil’s available nutrient levels, you may need to add fertilizers to have a successful crop.

Apply your fertilizer in two separate applications – once at planting time and the other after the plants are 8 to 18 inches tall. When planting sweet corn, select the right variety for the length of the growing season in your area. The quicker maturing varieties are recommended in our area, as our growing season sometimes is not very long.

There are three different kinds of sweet corn: su1, se1, and sh2.

These acronyms stand for the following: Standard Sweet Corn is su1, Sugary Enhanced is se1, and Supersweet is sh2.

Standard varieties do not have a long shelf life, as their sugars are very quickly converted to starches after harvest, which negatively impacts flavor. For standard varieties, you should keep the time between picking and cooking as short as possible, since after picking this corn loses its sweetness very quickly.

In the early morning hours, corn ears have their highest sugar content. For optimal flavor and sugar content, it is better to grow a se1 Sugary Enhanced or sh2 Supersweet variety.

Good varieties of se1 are Sugar Buns, Incredible, Kandy Korn, Ambrosia, Spring Treat, Bodacious, and Peaches and Cream. Good types of sh2 are Honey Select, Supersweet Jubilee, and Northern Xtra Sweet.

It is an important practice to isolate your corn patch from other varieties of corn depending upon the “level or kind of sweetness,” meaning the levels called “Standard Sweet Corn”, “Sugary Enhanced”, and “Supersweet”. Each of these three classes can cross-pollinate with varieties from the same class successfully, but shouldn’t be pollinating with the other ones.

For example, Supersweet varieties can pollinate other Supersweets, but shouldn’t pollinate Sugary Enhanced or Standard and vice versa. If pollinated from a variety that is not the same kind of sweetness, the corn kernels can have their flavor negatively impacted, and taste starchy instead of sweet.

For further questions on growing sweet corn, please contact Lance at the Fremont County Extension Office at (208) 624-3102.