Planting Date
The optimum planting date in this area is usually from mid March through April. With this planting date, most of the pollination will occur before the extremely hot temperatures hit, which usually occur from the middle of July to early August. Also, with most March and early April plantings there should be sufficient rainfall to insure that the permanent secondary root system (which develops above the seed) will be established. This root system forms about 1 inch below the soil level and must have moisture in order for the roots to develop. Good yields can be obtained by planting after April, but the risk from adverse temperatures and low humidities during pollination are increased.
Soil temperature should be at least 55ºF when planting. The minimum soil temperature at which corn will germinate is 45 to 50ºF. The optimum range is 80 to 90ºF. Corn planting is generally 10 days to 2 weeks after the average date of the last killing frost. Corn is able to recover from light freezes that occur before the plants are 6 inches tall. Varieties now in use, generally reach maturity in 130 to 175 days.
Planting Schedule
In order to begin harvesting as early as possible and to spread the harvest period, a grower may want to plant an early maturing variety first followed by medium and late varieties. Early harvested corn often brings a premium price (late August to early September). After the optimum planting time has passed, then again plant the early maturing varieties in order to complete harvesting before adverse weather conditions occur. In general, the early maturing varieties show more seedling vigor with early plantings under cool soil temperatures, than the later varieties. Seedling vigor differences are minimized as soil temperatures increase.
Planting
Planting is an extremely important operation in corn production. It is important that most of the corn seedlings emerge uniformly. In order to accomplish this, it is desirable to begin preparing a seed bed for planting in the fall or early in the spring. For corn, the most desirable type of seed bed is a fine, moist seed bed. Early formed beds are preferred for early plantings because the soil in the beds warms and dries faster in the spring and compaction in the seed row is eliminated compared to flat plantings.
The most extensively used method and most satisfactory, is to plant into moisture either from natural rainfall or from a pre-irrigation. Irrigating up is quite satisfactory with later planting when soil temperatures are warmer. However, with March and early April plantings, irrigating up may cool the soil too much for germination.
Planting Depth
Ideal planting depth is 2 to 2-1/2 inches. It is desirable to have approximately 1 inch of moist soil above the seed. If you have a fine, moist seed bed, 2 inches should be proper planting depth. Three inches are considered about as deep as we would like to see corn planted. If you plant quite deep early when the soil is cold, beating rains could cause a severe crust and the deep planted seed may not have enough energy to push through the crust and make a good stand. Crusts should always be broken if possible before the corn shoot contacts it.
Type of Planters
We do not like the old disc planter used for sugar beets except when used for planting in dry soil and irrigating up. It is difficult to uniformly place the seed into moisture with disc planters We much prefer the corn shoe or the long shoe type planters. The newer double disc planters with press wheels designed for corn are satisfactory.
The Planter
One of the most important parts of your planter which should be checked is the little knocker wheel. It is spring loaded and has a little round wheel which runs on the corn plate and pushes the kernels out of the planter. It is important that this wheel is not broken or badly worn and that the spring has good tension. If it is not working and if a slightly large seed comes into the plate, it may stick in the plate and cause a skip to occur while the kernel is stuck in the plate.

Corn Shoe Runners
When shoe runners become flat on the bottom and do not place the seed in a good moist groove, it can result in poor germination. Replace shoe bottoms when badly worn.

The Drive Wheel (which runs the planter)
Older planters have a narrow drive wheel and newer model planters have a wide drive wheel. The wider drive wheel has less tendency to slip and gives a more uniform planting. The narrow drive wheel can give uniform planting, but it requires a smoother seed bed, one that is not cloddy. The narrow drive wheel tends to slip in cloddy conditions because it does not have the traction of the wider wheel. A new, wide wheel can be put on some of the older planters. Growers should consider this, particularly in situations where they are planting in dry, cloddy conditions, and the drive wheel may have a tendency to slip.

New Planters
The new air planter, used to plant the Slater variety trials since 1989, has given very good populations for a wide range of seed sizes.

Bed Planting
There is increasing evidence that the growth and activity of the plant root system is a limiting factor in maximizing crop yields. One of the most recent new developments in cultural practices for corn grown on poorly drained saline and clay soils is the use of high 60 inch beds. Two rows of corn are planted on each bed. However, they must be planted closer than the normal 30 inches in order to make a deeper than normal furrow to produce the desired drainage effect. Examples of spacing that have been used include 22-38, 24-36, 26-34, 28-32, and 30-30. This bedding technique will partly reduce the injury from drowning and scalding that normally occurs under poorly drained conditions. The benefits from bed planting have also been dramatic in other crops such as wheat and alfalfa.

Growth of the Plant
At germination, the primary root system is the first structure to emerge from the seed. Typically, the primary root system consists of the radical and 3 seminal roots. Shortly after the primary root has emerged, the first internode elongates and pushes the coleoptile towards the soil surface. The length of the first internode depends upon the depth of the planting. The first internode increases in length until the node from which the coleoptile grows is within about 2 inches of the soil surface. This is one reason that corn can be planted deeper than small grains and still emerge. When the tip of the coleoptile is past the ground level, it splits and the first of the foliage leaves emerges through the split.
The main root system of the corn plant develops from the nodes above the seed near the ground level. They form from about an inch below the soil surface no matter how deep the seed is planted. Moisture must be available in this area in order for these roots to begin growing. Corn roots spread to about 3.5 feet and can penetrate to 10 feet or more in deep, permeable soil.

Plant Population
Most varieties are planted at 28,000 to 32,000 plants per acre.
Plant population is a key factor influencing corn yields. With the varieties now in use, it is important that they are planted at the proper populations for maximum yield and to avoid lodging. Consult your seed dealer for specific seeding rates. Most varieties usually require about 18 pounds per acre.
It is important that corn plants are spaced evenly down the rows. Corn has less ability to compensate for gaps in the stand and multiple dropped seeds than many other crops. A study in Kansas showed yield increases of from 200 to 1,200 pounds per acre where the plants were perfectly spaced versus the planting that was obtained with commercial planters. Therefore, it is important that the planters are operating properly and not too fast. Air planters can operate at a faster speed than ground driven plate flex planters.

Pollination
Corn is a naturally cross-pollinated crop. The pollen is distributed by wind and gravity from the tassel to the silks of the ears. The silks emerge in succession from the base to the tip in 2 to 5 days and are receptive to pollen whenever they emerge and remain receptive up to two weeks. The ears pollinate from the base to the tip. Thus, pollination occurs over several days. Each tassel sheds pollen for several days. A corn field will usually have plants shedding pollen over a 2-week period, thus assuring good pollination under most conditions. Many corn varieties now in use have some sterile tassels.
With corn, it is important that all of the plants emerge at the same time, so there is a good pollen supply available for all plants. For plants that emerge late, it is very likely there will be insufficient pollen for pollination.
Corn plants are quite susceptible to injury from high temperatures and low humidities at the tasseling stage. Pollen may not be produced or may dry up before pollination takes place, resulting in poor kernel set.
A distortion of silk growth (called jamming) is caused by high temperatures. In jamming, the silks grow first upward, then downward and sometimes up and down again with the husks, instead of growing straight up and emerging from the husk tip. The folded silks may finally emerge from the husks, although usually too late for pollination.

Rotation
Corn is usually grown in a rotation, but it does follow itself better than most crops. A build up of diseases has been noted in some fields planted to continuous corn. Two of the diseases have been fusarium stalk rot and charcoal stalk rot.