When to Harvest Sweet Corn

Physical Appearance

• Monitor the sweet corn ears for corn silk development. Ears reach maturity and are ready to harvest approximately 20 days after corn silk has emerged. When the corn silks ends have dried up and turned brown, check the firmness. Ears that are ready to harvest will feel firm when gently squeezed. Rounded rather than pointed ends are also indicative of maturity. Gently separate a portion of the husk in the middle of the ear. Mature kernels appear rounded and full. Puncture a kernel with a fingernail and observe the juice that comes out. If the fluid is clear, the corn is not mature; a milky fluid indicates mature corn; and a creamy fluid indicates the corn is over-mature.
  
  

Types

• While there are general guidelines for sweet corn crop maturity times, cool weather and lack of moisture will delay the maturation. Sweet corn harvest times vary from year to year and from location to location. According to Oregon State University, corn matures quicker in hot weather when there is adequate moisture. Areas that receive plentiful rainfall and consistently high temperatures produce crops sooner than areas that receive little rainfall and have cooler climates. On average, normal sugary types mature between 58 and 86 days, sugary enhancer between 66 and 89 days and super sweet between 70 and 85 days.
  
  

Time Limit

• Once sweet corn matures, harvest the ears within seven days. The sugars in sweet corn begin to turn into starch quickly. Once harvested, the process of the sugars becoming starch occurs rapidly. Harvest sweet corn ears immediately before cooking, then husk them, keep them moist and refrigerate them to slow the process of the sugars turning into starch. Pick sweet corn for freezing and canning during the morning hours before the ear uses extra fluids in the kernels for energy. Harvest, clean and process the ears immediately. Over-mature sweet corn ears are ideal for use in canning.