By Matthew R. March, MNRD
Polk County Extension Agent
Sweet corn is a favorite treat during summertime. Who doesn’t love eating sweet corn fresh off the cob? Sweet corn can be a challenging crop to grow in small gardens due to space issues, but if you have the garden space, sweet corn can be a great addition.
Believe it or not, sweet corn belongs to the grass family and has the same growth characteristics as the grass in your lawn. When selecting a site, well drained soils are preferred, but sweet corn can grow in a variety of soil conditions. Sweet corn is best suited for deeper soils, however, if your garden has sandy soils, you can still grow sweet corn. Magnesium deficiency is a common issue seen in sweet corn in sandy soils and you will need to add magnesium. Magnesium can be found in products such as K-MAG fertilizer and Epsom salt. Another issue you will see in Polk County soils is pH levels. Sweet corn grows best in soils with a pH between 5.5 and 7.0. Many soils in Polk County have a pH between 4.5 and 5.5. An application of lime can correct soil pH.
Block plantings or several short rows of sweet corn is required in small gardens instead of one or two long rows. This is because sweet corn is wind pollinated. Pollination will be ineffective when sweet corn is planted in single rows, thus affecting yields. When preparing the site, work the soil thoroughly to 10 inches and remove all weeds, rocks and trash. An application of fertilizer should occur right before or during planting. A soil test is preferred to determine exact amounts and type of fertilizer to add. However, a general recommendation is two to three pounds of 13-13-13 fertilizer for every 100 square feet.
Sweet corn should be planted as soon as the danger of the last frost has passed. Sweet corn is a crop that requires large amounts of water and the earlier you plant will help ensure sweet corn matures before the dry hot weather of summer. In Polk County, plantings should occur during the first half of March.
Watering should occur regularly to ensure the leaves do not wilt. Keep the soil weed-free and till the soil when the sweet corn is knee to waste high. A top dress application of nitrogen fertilizer should also occur at this time. Corn earworm is the most easily recognized pest in corn. Corn earworm is the worm, or larvae of a moth, that is present under the husk on the silk end of the corn cob. Control includes Sevin, Bt, and garlic juice extracts. European corn borer is another damaging pest in corn. As the name suggests, the borer feeds inside the stalk of the plant. Control options include Bt and garlic juice extracts.
To determine when sweet corn should be harvested you will need to pay attention to the tassel on top of the plant. Sweet corn is ready to be harvested about 3 weeks after the tassel emerges. To harvest, hold the stalk below the ear and twist the tip of the ear towards the ground until it breaks. Sweet corn should be eaten within one or two days of harvesting as the kernels begin to lose sweetness after two days.
Sweet corn can be a fun crop to grow in the garden, but it does have some challenges. The biggest issue affecting production in small gardens is planting in one or two long rows and from underwatering.