Several factors may contribute to planting wheat outside of recommended planting dates, including grazing intentions, weather delays, and late row crop harvest. Wheat yield potential is greatest in south central when planted between Sept. 25 and Oct. 20, and in southeast Kansas when planted between Oct. 5 and Oct. 25. 
A study begun in the fall of 1995 at the South Central Experiment Field near Hutchinson examined the effect of planting date on tiller number, spike production, and grain yield. 
Planting during the optimal time for a given region produces the ideal number of highly productive fall tillers and productive spring tillers, resulting in maximum spike production and grain yield.
However, wheat may need to be planted early under some situations. Early-planted wheat results in an overproduction of fall tillers, resulting in competition between plants and thus reducing the number spikes and overall yield in the spring. 
In addition to tiller competition, wheat planted early generally has a higher incidence of insects and disease. Hessian fly, aphids, and wheat curl mites are more likely to invade earlier-planted wheat causing damage and vectoring viral diseases such as barley yellow dwarf and wheat streak mosaic.
If planting early, the best management practice against insects and disease is to select resistant varieties with good yield potential. Systemic insecticide seed treatments may provide a benefit against some insects and the viral diseases they vector, however these can be costly and are an added expense if insects are not present. 
If planting is delayed past the optimal window, yield potential will likely be reduced, unless growing conditions are favorable. Planting later in the season will reduce the number of highly productive fall and productive spring tillers, reducing the overall yield potential.
If planting later than optimal, producers should increase their seeding rate to account for the limited time for fall tiller production by individual plants. Planting extremely late, into the winter, is not recommended, as yield potential will likely be very limited unless growing conditions are favorable.
A study conducted at the Southwest Research-Extension Center in Garden City examined planting dates from October through March. The results suggest that yield potential is reduced by greater than 40 percent when planted after the first of the year.
In addition to reduced yield potential, planting late in southeast Kansas increases the risk that wheat seedlings may not have enough time to vernalize prior to spring greenup.