How Deep Should You Plant Corn?

Growing Sweet Corn

• With more natural sugars than the other corn types, sweet corn (Zea saccharata or Zea rugosa) is a common garden crop. Sow two standard-sized corn seeds every 12 to 15 inches to a depth of 1 1/2 to 2 inches, in rows spaced 30 to 36 inches apart. When planting an “Xtra-Sweet” cultivar, decrease planting depth to 3/4 of an inch, with row spacing as close as 24 inches. Short-season cultivars such as the bi-color “Double Standard” and the old-fashioned “Fischer’s Earliest Corn” typically mature in 73 days or less. The longer season “Hopi Blue” can be eaten when still young and tender, or picked when fully mature at 110 days and allowed to dry.

Importance of Proper Depth

• Accurate planting depth is especially important to corn seeds, which need adequate soil-to-seed contact to absorb the 30 percent of their weight in water needed for germination. The deeper the soil, the more consistent the moisture levels. Corn planted at the proper depth also develops good nodal root systems -- the roots responsible for the majority of corn’s nutrient and water uptake. If your soil is extremely dry and you have limited access to water, alter the planting depth to provide better germination rates. When dealing with limited water, in clay soil, plant sweet corn as deep as 3 inches. Sow seeds up to 4 inches deep in silt, and increase the planting depth to 6 inches in sandy soil.

Growing Popcorn

• A surprisingly nutritious snack, popcorn (Zea mays everta) contains 67% as much protein as an equal portion of beef. The smallest of the corn seeds, popcorn should be planted close to the surface: 1 to 2 inches. Sow seeds 8 to 10 inches apart, in rows spaced as close as 24 inches. With both a slow germination rate and a slow growth rate, this crop matures in 85 to 120 days, depending on the cultivar. If you plan to sow popcorn near sweet corn, stagger the plantings by at least two weeks to avoid cross-pollination, which results in poor popping. Harvest the ears when the kernels turn glossy and hard. Beyond the basic yellow and white varieties, consider growing a specialty cultivar such as “Midnight Blue,” “Ruby Red,” “Turquoise” or “Strawberry.” Each has its own distinctive flavor.

General Growing Tips

• Before planting this heavy feeder, work 2 to 4 inches of compost into the soil and 1 pound of 16-16-8 fertilizer into every 100 square feet. To increase germination rates, soak the kernels in water overnight before planting. Although you might feel pressure to get this long-season crop in the ground, wait until the soil warms to the proper temperature before planting. According to Iowa State University Extension, corn planted in 50-degree-Fahrenheit soil takes up to three weeks to emerge, while seeds planted in 70-degree-Fahrenheit soil germinate in less than one week. When stalks are knee-high, hill soil up over the exposed roots to provide additional stability to the plant.