Perennial ryegrass is the best type of grass to use for a cool-season lawn in Phoenix. This is one of the most common types of grass used in the United States. There are several qualities of perennial ryegrass that allow it to be used for such a purpose. For example, perennial ryegrass has a dark color that remains intense throughout the winter. It has a great rate of survival during cold season as it has good cold tolerance. Moreover, it can also withstand light share and has a fast germination and seedling growth.