How to Tell When Sweet Corn Is Ready to Harvest

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Nothing compares to tender, sweet corn (Zea Mays) straight from the garden before its sugary sweetness has converted to starch. Harvesting it at the right stage and cooking it quickly is the secret to maintaining its sweet flavor and retaining the vitamins and minerals in the corn. Knowing when your corn is ready for picking and eating is important to preserving both the flavor and the texture of the kernels. Fortunately, determining when corn is ready for harvest isn't difficult.

Days to Maturity

The number of days to maturity listed on your seed packet or in the plant description gives you a good idea of when you can expect to harvest your corn. Each variety is different, of course, and days to maturity for corn ranges from 60 to 100 days. This is typically calculated via plant trials, usually conducted in a warm climate under ideal circumstances. If you live in a cool or northern climate, or the weather is not ideal for growing corn, it may mature later than the listed days to maturity. Use the days to maturity as your guide for when to expect mature corn, but don't expect it to be exact.

Change in Appearance

The appearance of your corn plants changes as they near the time for forming ears. The tall grasslike blades suddenly sprout a tassel at the top of the stalk. The tassel resembles a huge cluster of oats or wheat. Initially, the tassel is green, but as it matures and blooms, it turns brown. At this point, you will notice "silk" beginning to form on immature ears along the stalk, As the tassel blooms and releases pollen, it falls down onto the silk. This pollinates the corn, and the ears soon begin to grow. Watch your corn closely at this point, as the mature ears will be ready to harvest in approximately three weeks.

Ear Formation and Silk

After pollination, the silk on the ear of corn gradually turns from green or red/green to brown and eventually reaches nearly black. It becomes dry and brittle, signaling that the kernels have matured. The ear becomes plump and firm as the kernels "fill out." At this point, the foliage on your corn plants remains green and appears healthy.

Testing the Kernels

As the kernels grow, they transition from tiny white bumps to full kernels filled with a white, milky juice. This is referred to as the milk stage of corn and is the ideal time for harvesting, as the kernels are crisp and tender with an intense sweet flavor. Test the kernels by puncturing one with your finger. If it squirts white juice, it is ready for harvest. Kernels become tougher, and the insides become doughy as they pass the milk stage. While you can still eat corn past its prime, it is not as sweet because the sugar inside the kernel has been converted to starch.

Cooking and Storing Corn

Harvest corn as close to cooking time as possible to retain its flavor. It loses 50 percent of its flavor within 12 hours of harvest if not refrigerated, explains the Purdue University Extension. If you must store corn, keep it slightly above freezing.