By National Gardening Association Editors, June 23, 2008
- Plant corn directly outdoors after all danger of frost has passed and the soil temperature is about 60° F.
Seeds can be started indoors, two seeds per peat pot, 3 to 4 weeks before the last frost date.
Plan the garden to prevent cross-pollination between incompatible types of corn and to prevent tall varieties from shading nearby crops.
- Work plenty of manure into the soil the previous fall.
- Just before planting, sprinkle 3 to 4 pounds of 5-10-10 or equivalent fertilizer per 100 feet of row along the side of each row and work it into the soil.
- Plant corn seeds in blocks of at least four rows with 2 to 4 feet between rows (the closer spacing is for short varieties). Sow the seeds 1 1/2 to 2 inches deep, 6 to 8 inches apart.
- Thin the corn to stand 12 to 16 inches apart when the plants are 4 to 5 inches tall.
Provide at least 1 inch of water a week.
Control weeds with frequent shallow cultivation until the plants are knee high. Then apply a 3- to 5-inch layer of mulch.
Side-dress with a high-nitrogen fertilizer, such as 2 pounds of ammonium nitrate per 100 feet of row, when the plants are 8 to 10 inches tail and again when the silks appear.
Watch for signs of nitrogen deficiency (yellowing leaves) and respond with quick side-dressings of fish emulsion, manure, commercial fertilizer, or a combination of the three.
See our article Summer's Bad Guys by Charlie Nardozzi for controls of common corn pests such as corn earworms and European corn borers.
- Sweet corn should be harvested when its ears are completely filled out and a pierced kernel shows a milky white liquid.
Sweet corn varieties (except for supersweet varieties) lose their sweetness soon after harvest. Immediately after picking prepare the ears for eating or preserving.
Harvest corn for meal or popping as late as possible and dry on the cob, then store.