Normally sweet corn is ready for harvest about 17 –24 days after the first silk strands appear. This can occur more quickly in hot weather and more slowly in cool weather.
Harvest corn when the husks are still green, silks are dry brown, and kernels are full sized and yellow or white in color to the very tip of the ear. Experienced gardeners can feel the outside of the husk and tell when the cob has filled out. Harvest corn at the “milk stage”, use your thumbnail to puncture a kernel. If the liquid is clear, the corn is immature, if it’s milky, it’s ready, and if there is no sap, you too late.
And here's the best tip in the game: Cover unharvested ears checked by this method with a paper bag to prevent insect or bird damage!
For corn that you'll be storing for a day or two, pick in the cool temperatures of early morning to prevent the ears from building up an excess of field heat, which causes a more rapid conversion of sugars to starch.
The best time to pick is just before eating the corn; country cooks say to have the pot of water coming to a boil as you are picking the corn, husking it on the way from the garden to the house! This is an exaggeration, but with standard varieties, sugar conversion to starch is rather rapid.
For any corn picked in the midday sun - plunge the ears in cold water or put them on ice for a short time to guard against the effects of field heat. Then, just store it in the refrigerator until you're ready to eat!
Extra-sweet varieties will also benefit from this treatment, but they are not as finicky because they have a higher sugar content and they hold their sweetness longer. The conversion of sugars to starch is also not as rapid in the newer super sweet types.
Now that you know how to harvest your garden-fresh corn, let's get cooking...
Fresh Corn Soup with Poblano Chile
2 Tablespoons extra virgin olive oil
1 medium onion minced
1 medium carrot, minced
1 teaspoon dried thyme
1 teaspoon dried basil
1/4 teaspoon cayenne pepper, or to taste
4 cups corn kernels, about 6 ears
4 cups low sodium vegetable stock
Salt and freshly ground pepper to taste
2 poblano chiles, roasted, skinned, and chopped
1/4 cup cilantro, finely chopped
I left out the 1 ounce of queso fresco or feta cheese whisked with 1-2 tablespoons of milk.
Heat oil in a large pot. Sweat the onions covered for about 5 minutes. Add carrots, cover, and cook another five minutes. Add garlic, dried herbs, cayenne, and cook covered another couple minutes. Add corn, season with salt, cover then cook another five minutes. Add vegetable stock, bring to a boil, cover and remove from the heat. Puree in a blender then strain through a fine mesh sieve. (Be sure to have a pot under the strainer to catch the soup ---- I have made this mistake before and don't want you to). Return soup to the big pot and season to taste.
I roasted the poblanos directly over the flame of the gas stove until they were blackened, put them in a ziploc bag to steam for awhile, then could easily remove the skins.
Ladle the soup into bowls. Stir in the poblanos and cilantro and serve.
This recipe is from the website of Kaiser Permanente, Food for Health, Recipes for Life.