Like their spring counterparts, the ideal seeding depth for winter wheat and rye is right around 1.5". It is the sweet spot between good seed-to-soil contact (and with that, access to moisture) and quick emergence. Seed shallower, and you risk the seed not imbibing enough water to germinate, or the seedling not rooting deep enough quickly enough to sustain itself. Seed deeper and you delay emergence, or worse, the coleoptile does not reach the surface, resulting invariably in a reduced stand. 

Soil moisture is a rare commodity across much of Minnesota. The drought monitor has 95% of the state rated as abnormally dry or worse. That begs the question: Do I stick with the ideal seeding depth of 1.5"  or do I dare seed into moisture? There is no simple answer, but I tend to lean towards seeding into moisture rather than sticking to the ideal seeding depth and hoping for rain. After all, September is drier than the preceding three months, while any soil moisture reserves were depleted by the crop you are seeding into.

Of all the small grains, barley has, on average, the shortest coleoptiles, followed by wheat and triticale. Rye has the longest coleoptiles. The table below shows the maximum coleoptile lengths of a few winter wheat and rye varieties. Coleoptile length correlates reasonably well with overall plant height within a species. Do not be afraid to seed winter wheat to a depth of 2.5" and winter rye to a depth of 3-plus inches. Compared to spring seeding, soils this time of year are much warmer. This partially offsets the longer time it takes for the coleoptile to reach the surface, helping germination and emergence.

Table 1 - The average coleoptile length of a few winter wheat and rye varieties using a modified ragdoll germination test in the absence of ambient light.