Rye grass is normally planted in the early spring or late summer when the soil temperature is 50 to 60 degrees Fahrenheit. The seeds germinate in three to five days creating a good stand of grass within four weeks.
Rye grass favors cool, moist climates and grow best in the early spring and fall. The optimal growing temperature is between 68 to 77 degrees Fahrenheit.
Rye grass becomes dormant during the hot, dry months of summer. Daytime temperatures above 86 degrees Fahrenheit and night temperatures above 77 degrees Fahrenheit trigger the dormant state even when the crop is watered regularly.