Productivity & Harvest
Yields for processing corn average between 4 and 6 tons per acre. For fresh market varieties, expect between 17,000-20,000 ears/acre (1,000 and 1,200 dozen) per acre. Higher yields, upwards of 2,000 dozen ears per acre, can be obtained with careful irrigation and nutrient management.
Most sweet corn is ready 15 to 22 days after silking, and is hand harvested by grasping the ear and pulling downward while twisting the wrist to snap the ear off the stalk. Sweet corn may also be harvested using machines, which are becoming more common. As the kernels mature, they pass through growth stages termed pre-milk, milk, early dough, and dough. At the dough stage, sugars in the kernels’ pericarp change to starch and the kernels become tough. The time to harvest is when kernels just reach the milk stage. Look for the following
- Kernels will be nearly full-size, but still soft and tender and filled with clear to milky juice when punctured with the thumbnail.
- The tip of the ear will be filled out.
- Silks will be dried and brown beyond the end of the husk (Fig. 10.4)
Figure 10.4 Harvest corn after the silks have dried and browned.
Harvest when 70% of the ears in the patch are in this condition. Sweet corn may only stay in prime condition for 1 to 2 days if daytime temperatures are consistently above 86°F, so harvest timing is critical for optimal flavor and quality.