Sweet corn, scientifically known as Zea mays var. saccharata, is a seasonal delicacy. The “corn season” refers to the short window when this sweet variety is picked at its peak sugar content. Because the quality and flavor of sweet corn degrade rapidly after harvest, understanding its seasonality is the most important factor in finding the best ears.
The General Seasonal Window
The national sweet corn season in the Northern Hemisphere spans from late spring through early fall. This timeline allows for a continuous supply to reach markets across the country for several months. The earliest harvests can begin as early as May in the warmest regions, signaling the start of the summer corn supply.
Peak availability and the highest volume of market supply occur between July and August, coinciding with the height of summer across the United States. While the bulk of the harvest is completed by the end of August, the season can extend into late September or early October in some northern regions before the first hard frost arrives.
Regional Differences in Availability
The sweet corn season does not arrive uniformly but rather “travels” geographically, with localized availability dictated by climate and planting times. Southern states like Florida and parts of California are the first to bring corn to market, often starting in the spring due to warmer weather. The early corn supply for the entire country frequently originates from these regions in May and June.
As summer progresses, the season moves northward along the East Coast, with harvests beginning in states like Georgia, North Carolina, and Delaware. By mid-to-late July, local sweet corn begins to appear in the Northeast and the Midwest’s growing regions. These northern areas enjoy their local peak period from mid-July through early September.
Defining Peak Sweetness and Freshness
The intense flavor of fresh sweet corn is related to a genetic mutation that causes the kernel to store sugar instead of immediately converting it to starch. This conversion process does not stop at harvest, making the time between picking and eating time-sensitive. Sweet corn has a high respiration rate after it is picked, causing the sugars to rapidly convert into starch and diminishing sweetness.
At room temperature, an ear of corn can lose a significant portion of its sugar content within 24 hours. This explains why the best corn is often purchased directly from a farm stand shortly after it was picked. To identify corn at its peak, consumers should look for ears with vibrant green, tightly secured husks, and silks that are brown and dry at the tip.
The traditional test for ripeness is known as the “milk stage,” where puncturing a kernel with a fingernail should release a milky white liquid. If the liquid is clear, the corn was picked too early; if it is thick and doughy, the sugar has already converted significantly into starch. Modern varieties, such as the “supersweet” (sh2) types, have been bred to slow this conversion, allowing the corn to retain its sweetness longer than older varieties.