Sweet corn is a summer treat that's best served fresh; there's no comparison between store-bought corn, and corn taken straight from the garden. Corn requires long, warm days, consistent water and lots of nitrogen. Some varieties take up to 120 days to mature. It also requires room. Each plant should have about 3 square feet of soil to produce two ears of corn. Harvest the corn 17 or 18 days after the silks first appear. Use a perforated, heavier plastic in colder areas with later spring frosts. The corn can grow under that type of plastic for 30 days, according to the University of Missouri.
Soak the corn seeds for 24 hours in water in a warm place if all danger of frost has passed. Soaked corn planted in cold soil may rot before it sprouts.
Dig up the area where the corn is to be planted. Add compost and any required soil amendments. Check with your local university agricultural extension to see what might be needed. For example, soils in the desert areas of the U.S. Southwest are alkaline and don't have much organic matter. Adding gypsum and compost improves the soil.
Add a fertilizer that is high in nitrogen, per package directions. Corn needs to grow quickly. If it's stunted from lack of fertilizer or water, it will stop growing and then restart. However, the tassels--the male flowers at the top of the stalk--may bloom before the silks, the female flowers that produce the corn kernels, are ready.
Dig a trough that is 1 inch deep. Remove the seeds from the water and plant 6 inches apart. Cover the seed. Water until the soil is wet to a depth of 4 inches. Use a screwdriver to check the depth.
Plant rows 36 inches apart. A block of corn is better than one or two long rows of corn. A block can be three or four rows, or more. So instead of planting two 15-foot-long rows, plant six short rows each 5 feet long and 26 inches apart. The pollen from the male flowers falls on the female flowers below. A block of corn increases the chance of pollination.
Lay clear plastic (kitchen wrap will work) over the row. Secure it with rocks or 2-by-4 pieces of wood. Or bury the edges under the soil. Kitchen wrap may have to be replaced several times, as it's not as sturdy as thicker plastic.
Check the soil's moisture every four or five days. When the soil is dry to a depth of 1 inch, remove the plastic and water to a depth of 4 inches, then replace the plastic.
As soon as the corn sprouts, cut an "X" in the plastic so the corn can get through it. Thin the sprouts to 12 inches apart. Remove the plastic when the corn is 12 inches high.