Grow your own organic sweet corn at home

Story and Photos by Kristi Cook

My garden is a living quilt composed of each family member’s favorites. For my daughter, there’s purple asparagus to announce spring’s arrival. For my husband, it’s jungle-like plantings of okra destined for the fryer. And for my littlest one, I grow juicy sweet corn that clings to his chin and makes him smile. However, unlike the other organic crops I grow, my research into organic corn culture produced very little advice. Despite this, over time I’ve learned how to not only grow our year’s worth of sweet corn organically, but I do so without complications from pests or disease.

Begin daily inspections at least two weeks before expected maturity. Feel for full, plump kernels through the husks. Once ripe, silks will begin to brown and pierced kernels will often, but not always, emit a milky liquid.

Prepare the soil
Several months before the anticipated planting date, have a good quality soil test performed and adjust pH to 6.0-6.5. You’ll also want to start the soil building process with 2 inches of compost or well-rotted manure. If preparing soil in the fall, follow with a nitrogen-building cover crop such as hairy vetch or alfalfa and turn under at least two weeks before the planting date. 

At planting, apply an additional 1-2 inches of compost or rotted manure, as well as a high-nitrogen organic fertilizer such as blood or cottonseed meal, especially if you didn’t have a nitrogen-building cover crop. Once stalks reach 12 inches, side-dress with an organic nitrogen source and again when tassels appear.

A heavy layer of organic mulch placed between the narrowly spaced rows is sufficient for weed suppression without the use of herbicides. The minimal weed growth near the stalks doesn’t harm production.

Perfect timing
Careful monitoring of soil temps is critical to avoid rotting seed. While some treated seeds may withstand temps as low as 55 F, organic untreated seed typically requires a minimum soil temp of 65 F. Once the soil warms, plant seeds ½-1 inch deep and then gently tamp soil. Space rows 24 inches apart in blocks of at least three to four rows to ensure adequate pollination. 

Apply organic mulch between rows; however, keep rows free of mulch until time to thin. Once stalks reach 6 inches, thin to 6-12 inches apart and mulch up to, but not touching, the stalks. Personally, I have found that the close spacing often limits weed growth in the rows to a manageable amount, so I often forego this additional mulching.

Growing stately organic sweet corn is a simple matter of following the basic tenets of organic gardening –organic soil building, organic fertilizers and/or cover crops, quality organic seed, and a healthy ecosystem.

Harvest time
If the raccoons have started raiding your garden, the corn is ready! However, a better way is to begin daily checks about two weeks before expected maturity, feeling for full, plump kernels. Once you think you have one ready, peel back a little husk and pierce a kernel. If milky juice oozes out, the corn is ready. Harvest in the early morning and refrigerate immediately.

Sweet corn is a heavy feeder, often requiring an organic source of nitrogen such as blood or cottonseed meal at planting, when stalks are 12 inches tall, and again when tassels appear.

Pest and disease control
I’ll be honest. Because I garden solely using organic methods, I have never had a pest or disease problem significant enough to warrant intervention in nearly 20 years of gardening. Between the birds, ladybugs, frogs, and other garden helpers, pests don’t stand a chance. As for disease, my healthy soil, crop rotation, and seed selection keep disease to a minimum. 

However, that’s not to say it won’t ever happen, so I like to be prepared for the two most common ailments – earworms and corn smut. The safest organic remedy for earworms is to apply five or six drops of vegetable oil in the tip of newly forming ears. You can add Bacillus thuringiensis (Bt) to the oil to help destroy any emerging earworms that made it past the oil. As for disease, if you see black, swollen kernels – known as corn smut – simply remove infected ears to avoid spreading this fungal disease. 

Growing your own organic sweet corn is a gardener’s treasure. And while some may insist it can’t be done, in reality it is more than possible with solid soil building practices, organic fertilization, and a healthy ecosystem.




Here are some corn types to try in your garden

Standard (su) 
The oldest and possibly easiest sweet corn to grow, standards offer both hybrid and open-pollinated varieties. The downside is sugars begin converting to starch immediately following harvest, which reduces sweetness. 
‘Early Sunglow’, ‘Jubilee’, ‘Silver Queen’ 

Sugary Extender (se)
With a higher sugar content than su types, these varieties retain sweetness up to four days following harvest with refrigeration.
‘Sugar Buns’, ‘Peaches & Cream’

Supersweet (sh2)
Also known as shrunken-2, supersweets boast up to 10 times the sugar content of su types and store up to 10 days with minimal loss of sweetness. However, sh2s require higher soil temps so careful attention to planting conditions is a must. 
‘Early Xtra Sweet’, ‘Jubilee’

Synergistic (sy)
Synergistic types contain a mixture of su, se, and sh2 kernels throughout the cob, offering benefits of each. 
‘Honey Select’, ‘Cinderella’

Augmented Supersweet
Similar to synergistic, this type has 100 percent sh2 kernels with some variation of se and su genes within the sh2 kernels. 
‘Triumph’, ‘Devotion’

Genetically Modified/Engineered 
Also known as GM or GE corn, these varieties are not suitable for organic practices. 
‘Roundup Ready’, ‘Liberty Link’, ‘Attribute’, ‘Performance Series’

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