Cover crop seeding dates established for control of soil erosion may differ from those needed for cover crops to be effective in taking up end-of-season nitrogen, and nitrogen from fall-applied manure. Rye and oat cover crops were seeded on six dates at two week intervals from August 18 to October 27, 2004 at the University of Massachusetts Amherst Crops Research and Education Center farm. The cover crops were seeded into plots 10 m long with 7 rows 15 cm apart. Nitrogen fertilizer was applied to the field plots at the rate of 67 kg/ha on the day of seeding to simulate a fall application of manure. Soil samples were collected at three depths prior to seeding the first cover crops on August 18, 2004, and then at two week intervals until the soil froze in November. Soil samples were also taken from each plot (for all six seeding dates) in mid-April 2005. Plant samples were collected every two weeks beginning four weeks after the seeding of cover crops at each date, and in April. The fall temperatures were warmer than normal in 2004 meaning late planted cover crops had better growing conditions than is usual at this site. Seeding either cover crop species in October gave insufficient cover for erosion control. Oat cover crops winterkilled and a mid-September date at this site would have been needed for sufficient cover during winter and spring. Preliminary data suggests that cover crops need to be seeded one to two weeks earlier for nitrogen uptake compared to seeding dates for control of soil erosion during winter.