When wheat is planted 3-4 weeks after the fly-free-safe date, the same yield can be achieved as earlier planted wheat if freezing weather does not occur until late November or early December. However, a higher seeding rate is recommended. For wheat planted 3-4 weeks after the fly-free-safe date, use a seeding rate of 1.6 to 2.0 million seeds per acre. The actual number of seeds per pound and germination rate are important for determining the correct seeding rate and drill calibration (Table 1). There are fewer seeds per pound of large seeds than pounds of small seeds. The number of seeds per pound can be found on the seed bag.
Table 1. Pounds of seed needed to plant from 1.2 to 2.0 million seeds/acre with seed of varying size.

Additionally, late planting also means plants will be smaller than normal when entering dormancy and have smaller, more shallow root systems, making them more susceptible to heaving next March. The best heaving control is to get the seed placed between 1.0 and 1.5 inches deep when planting and to plant no-till. These two practices combined will reduce heaving potential.
Source : osu.edu