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 tender kernels produce a milky juice. Sweet corn that is past its prime is tough and doughy. An immature ear will not be completely filled to the tip and the kernels will 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 to 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 one or two 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 will remain in prime condition for only one or two days during hot (85 F and above) weather. Check the sweet corn 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 sweet corn immediately as its quality rapidly declines after harvest. Sweet corn may be refrigerated for a short period (4-8 days) at 32 F. New high sugar varieties are slower to convert sugar to starch and may be harvested over a longer period of time. The high sugar types also have a longer storage life.
This article originally appeared in the July 1, 1992 issue, p. 116.
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