Harvesting sweet corn at the proper stage of maturity is essential to ensure a high-quality crop.
Sweet corn should be harvested at the milk stage. At this stage, the silks are brown and dry at the ear tip. When punctured with a thumbnail, the soft kernels produce a milky juice. Overmature sweet corn is tough and doughy. An immature ear is not completely filled to the tip, and the kernels produce a clear, watery liquid when punctured.
The harvest date can be estimated by noting the date of silk emergence. The number of days from silk emergence to harvest is approximately 18 23 days. Prime maturity, however, may be reached in 15 days or less if day and night temperatures are exceptionally warm. Most hybrid sweet corn varieties produce two ears per plant. The upper ear usually matures 1 or 2 days before the lower ear.
Sweet corn remains in the milk stage for a short time. The weather determines the length of this stage. Sweet corn remains in prime condition for only 1 or 2 days during hot (85 F and above) weather. As the sweet corn approaches maturity, check it frequently during typical summer weather to ensure high quality sweet corn.
Harvest sweet corn by grasping the ear at its base and then twisting downward. Use or refrigerate sweet corn immediately because its quality rapidly declines after harvest. If not refrigerated, standard sweet corn (su) varieties may lose 50% of their sugar content within 12 hours of harvest. Optimum storage conditions for sweet corn are a temperature of 32 F and a relative humidity of 95%. The maximum storage life for sweet corn is 4 8 days. Sugar-enhanced (se) and supersweet (sh2) varieties are slower to convert sugar to starch and may be harvested over a longer period. They also have a longer storage life.
Miniature ears of corn ( baby corn ) are popular items in restaurants and gourmet food stores. Although Bonus and a few other varieties are grown specifically for their miniature ears, most baby corn is actually grown from regular sweet and field corn varieties. The ears are harvested when they are 2 4 inches in length and 1/3 to 2/3 inch in diameter at their base. Most sweet corn varieties reach this stage 1 3 days after the silks become visible.
This article originally appeared in the 7/11/2003 issue.