Annual ryegrass is quite similar to perennial ryegrass except it is an annual or biennial, depending on climate and/or length of growing season. These grasses have a wide range of adaptability to soils but thrive on dark rich soils in regions having mild climates. They do not withstand hot, dry weather or severe winters. They will stand fairly wet soils with reasonably good surface drainage. Annual ryegrass is distributed throughout the entire United States.