self-propelled or tractor-drawn farm machine for cutting grain and laying the stalks in windrows for later threshing and cleaning. The modern descendant of the header, the windrower is used to harvest grain in parts of the United States, Canada, and the “new lands” in Siberia in which certain conditions, such as high moisture content and uneven ripening, make direct combine harvesting impractical. Because grain cut by windrowers dries to a moisture content suitable for threshing, harvesting may be done a week or 10 days earlier than by combine, reducing grain losses considerably.

A windrower usually consists of a cutter bar driven by an engine or powered by a shaft from the tractor, a reel to sweep the grain onto a platform, and a canvas conveyor to carry it to one side and deposit it in a windrow for drying.