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Summer Sweetcorn: Midwest Magic

Sweetcorn in the summer, fresh from the field, hot out of the pot. That is a potent memory for any kid lucky enough to grow up in the Midwest. For those of you that are thinking about recapturing some of those childhood memories, there is great news. Modern sweetcorn hybrids are available that make it easier to bring quality corn to the table. To get that delicious ear of memory, however, there are a few things you must do to assure success. Read this article to successfully grow your sweetcorn memories.

Jim Lakin MD, Master Gardner

Summer Sweetcorn:  Midwest Magic

First, it’s a good idea to get your soil tested.  The University Extension can do that inexpensively (  Apply phosphorus and potassium as recommended by the test results.  Corn grows best in well-drained, organic-rich soil at a pH around 5.8 to 7.0.  The soil test can help getting the pH right.  Working organic mulch and/or compost into the soil will also increase its richness.  If you have any questions, you can contact the University Extension for help (

When planting the seeds (kernels) you should sew at least four rows.  To produce, the corn must either self or cross-pollinate with a similar variety.  If the wind does not blow the pollen from stalk to stalk, blank spots will appear on the ears, where pollination failed.  That’s why you want your cornstalks huddled together.  Wait until the soil temperature is at least 60o.  Plant the kernels about an inch deep 30 to 36 inches apart.  It probably is best just to plant one variety of sweetcorn in a small garden.  If different strains cross-pollinate the result is usually an ear with poorer flavor and texture.

Once the seedlings sprout, you’ll want to keep up the watering.  Drought can badly stress the developing ears and greatly reduce quality.  About an inch of water a week usually does the trick.  You will also want to start hoeing before the weeds get out of hand.  When cultivating, use a shallow stroke just below the soil surface.  Sweetcorn roots are shallower than field corn so you don’t want to get too vigorous and damage your plants.  As the corn gets taller it will tend to shadow out the weeds and make your job easier. 


The most common corn insect pests are the European corn borer and the corn earworm.  If you do find a caterpillar near the tip of the ear as you husk it, don’t be alarmed.  They are common.  Cut the affected part off and cook the rest.  A lot of insect problems can be avoided by delaying planting until the soil has warmed to 60o (usually by mid-May) and using a variety that will mature in less than 80 days.    

You should harvest your corn when the kernels in the center of the ear are full and “milky” when squeezed.  You should watch for this when the silks start to brown and dry.  This usually happens about 18 to 24 days after they first appear.  Of course, you’ll want to eat as much as you can while it is fresh, but once you‘ve had your fill there are several ways to preserve your harvest.  Depending on the variety you can store the ears in the refrigerator for one to seven days before they lose their flavor.  If you want to can the corn you must use a pressure canner.  If you have the space, freezing is an excellent way to preserve sweetcorn.  We have removed the kernels from the cob, boiled and bagged before freezing with great corn, months after August harvest. 

Photo credits: University of Minnesota Extension (all)

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