Rough pigweed normally begins growth in late spring and matures in late
summer or early fall . It blooms in the Great Plains from July to
October , and in the central and northeastern United States and
adjacent Canada from August to October . It blooms in southern
California from June to November , in Montana from June to October,
in North Dakota and Wyoming from July to September  and in the
Carolinas from July until frost .
- 7. Dittberner, Phillip L.; Olson, Michael R. 1983. The plant information network (PIN) data base: Colorado, Montana, North Dakota, Utah, and Wyoming. FWS/OBS-83/86. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 786 p. 
- 11. Fernald, Merritt Lyndon. 1950. Gray's manual of botany. [Corrections supplied by R. C. Rollins]
- 14. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. 
- 27. Munz, Philip A. 1974. A flora of southern California. Berkeley, CA: University of California Press. 1086 p. 
- 31. Radford, Albert E.; Ahles, Harry E.; Bell, C. Ritchie. 1968. Manual of the vascular flora of the Carolinas. Chapel Hill, NC: The University of North Carolina Press. 1183 p. 
- 44. Whitson, Tom D., ed. 1987. Weeds and poisonous plants of Wyoming and Utah. Res. Rep. 116-USU. Laramie, WY: University of Wyoming, College of Agriculture, Cooperative Extension Service. 281 p. 
No one has provided updates yet.