Growing sweet corn seems like a simple enough venture, after all, there are acres and acres of it grown throughout the country every year. However, for such a seemingly simple plant, sweet corn has some distinctive complexities that gardeners and growers should know.
Choosing a named variety that performs well in your zone and specific location is an important first step to enhancing your chances of plants yielding healthy and flavorful sweet corn. However, there are many cultural and environmental factors that determine the quality and number of ears produced. At every growth stage, corn can be positively or adversely influenced by the weather, field conditions, available moisture, and soil nutrition.
- Variety Selection - What variety is recommended for your location? What genetic characteristics are most desirable for your location, growing conditions, and your personal preferences? Ask your county ag extension service what they recommend for your area. Is that Su, Se, or Se+, Sh2, Synergistic, or Quad sweet types?
- Proper Soil Nutrition - A balance of nutrients is important, but the available nitrogen is most critical. If you have not had a soil test done within the last 3 years, have one done prior to planting? Those test results and information will indicate what nutrients are needed and in what amounts.
- Plant Population - Knowing the optimum plant density for the type of sweet corn you are planting is necessary. Plant populations for modern hybrids are much higher (28K to 40K per acre) than plant populations of popcorn, or open-pollinated types, which are usually less than 18K plants per acre. If you are planting a small garden space, a minimum of 4 rows are required for proper pollination, but the more rows you plant the better.
- Soil Cultivation - Cultivation of soil, timing, and frequency all relate to and can have an effect on other yield factors like nitrogen absorption, plant population, and crop rotations.
- Previously Planted Crops - Rotate corn crops in a 3-year planting sequence, alternating with nitrogen-fixing cover crops or legume garden crops is highly beneficial to help replace nitrogen for heavy feeding corn and for helping to reduce potential pest populations.
- The Weather - The weather is the single largest factor affecting yield and will have a significant influence on all these other factors. Control things that are controllable and hope for favorable weather conditions. This is all gardeners or growers can do to try to get the best yield possible. In some years, yields will be less than others, this is just the nature of raising vegetables.
Flavor Quality Factors:
- Hybrid Selection - Know what to expect when it comes to sweetness variability. Su or normal sugary varieties ripen with about 5 to 10 % sugar per kernel. Se, sugary enhanced types, will typically produce kernels with 12 to 20% sugar with a thinner pericarp (skin of the kernel). Sh2 or super sweet varieties come in at 20 to 30% sugar per kernel on average, but they struggle to germinate in cold, wet soils and have a much thicker pericarp.
- Crop Maturity - Harvest of any sweet corn should happen in the R3 milk stage when sugars, starch, and moisture are at the optimum point. Corn picked before this stage will have small kernels, lack color, and have a watery flavor. Corn picked after this peak maturity stage will have doughy, pithy, and undesirable kernels. Rapid starch accumulation happens quickly if ears are not harvested from the field at peak ripeness.
- Cross Pollination - In the Midwest and other places where a great deal of corn is grown, adverse cross-pollination of sweet corn is a continual concern. Always follow recommended isolation rules for whatever type of hybrid you choose to grow. As well as isolating white kernel corns from yellow or bicolor varieties. We cannot emphasize enough that kernel quality and overall flavor will be significantly altered if distance or planting time isolation rules are not followed. (600 ft. distance OR a 2 to 3 weeks staggered planting time is sufficient)
- Time to Harvest - As mentioned, within crop maturity and proper storage, the quality of any sweet corn will decline as soon as it is harvested. The savvy farmer picks and eats their sweet corn the same day. Pick sweet corn when the inner fluid achieves the "milky" look when pierced with a thumbnail. The length of time to optimal harvest depends on growth stages. (Review Sweet Corn Maturity Stages Garden Guide)
- Proper Storage - Fresh harvested sweet corn should be stored at a temperature as close to freezing as possible with high relative humidity to maintain its flavor. Limit storage to a short period of time. Conversion of sugar to starch occurs no matter what but it speeds up in warmer temperatures and the longer ears sit.
- The Weather - Always the elephant in the room. Environmental stress like drought, cold, or wet conditions at the wrong time or stress during some of the critical vegetative or reproductive development stages and a crop can be ruined or significantly impacted.
(For more information, please review our other Garden Guides regarding Sweet Corn.)
Simple, yet Complex
Virtually all modern sweet corn hybrids have been bred with increased sugar content. Breeding also provides vigorous growth, requiring attention to soil nutrition and available water. Some varieties have important disease resistance, but sweet corn is a seemingly simple plant with complex growth stages that require close attention in order to yield well with flavorful, healthy ears and kernels. Often, trial and error is needed to find the right variety for your location. Keep trying different varieties and types until you find the one that performs most consistently for your garden, growing conditions, and techniques.