Green and yellow foxtail [Setaria viridis (L.) Beauv. #3 SETVI and S. glauca (L.) Beauv. #SETLU] seed germination after 14 days were similar at 15, 20, and 25 C. However, at 10, 30, and 35 C, green foxtail seed germination was higher than that of yellow foxtail, indicating that temperature extremes influenced green foxtail seed germination less than that of yellow foxtail. Seed germination of both species was initiated at about the same time; however, green foxtail seed germinated 1 to 2 days faster than yellow foxtail at all temperatures. After 72 h in −4 bars osmotic potential solution at 25 C, green foxtail seed germination was 70% compared to 12% for yellow foxtail, suggesting that green foxtail seed may germinate more rapidly than yellow foxtail seed in soils with limited moisture.