Perennial Ryegrass: lolium perenne

The PropertyClub Team
Nov 6th 2020
Used widely throughout the US, perennial ryegrass (lolium perenne) is one of the most common types of grass for homeowners. Ryegrass is favored because it has a fast germination rate and establishes itself quickly. When planted and taken care of, perennial ryegrass forms lush, fine-bladed grass that keeps its color and body even through the cold months of the winter.

Perennial ryegrass is often used in pastures for livestock. Despite its name, perennial ryegrass is not related to the rye plant. It is a cool-season grass that typically grows the best in the colder months, from fall to spring. The best places to grow perennial ryegrass are in colder climates in the north and eastern United States. 

Perennial ryegrass is not as hearty as some other forms of grass such as bluegrass or tall fescue, but it is one of the more popular types of grass when combined with other species. 

Does Perennial Ryegrass Come Back Every Year?

As the name would imply, yes, perennial ryegrass goes through its growing season in the fall and winter, then goes dormant during the high-heat, low-moisture months of the summer. It then will reawaken and come back during the next winter. Even though perennial ryegrass is best suited for colder climates, southern lawn owners find a great use for it when their warm-season grasses go dormant in the winter. 

As such, many people mix perennial ryegrass with other types of warm-season grasses so they can have a green lawn year-round. Perennial ryegrass will grow and thicken during the winter, then warm-season grasses can pick up the slack during the summer. 

Does Perennial Ryegrass Die in the Summer?

It depends on the specific climate that you live in. Generally, summer is a dormant period for ryegrass. Once temperatures reach around 87 degrees-F, perennial ryegrass will go dormant and stop growing. This does not kill the grass though, as it will reawaken and start thriving once the temperatures drop. 

However, prolonged, hot temperatures over 100 degrees-F will kill perennial ryegrass due to lack of moisture. This is one reason perennial ryegrass is not as common in the south and southwest United States. The arid hot summers are not suitable for ryegrass, and it can die and not come back. 

However, in colder climates, ryegrass will not die in the summer and should come back in the winter, assuming that it is properly maintained and taken care of. 

That being said, perennial ryegrass is not suited for prolonged exposure in frigid weather either. Prolonged temperatures under 30 degrees-F can stunt its growth and kill it. You can avoid most of this damage if you keep your soil nutrient-rich and well-watered. The water will produce heat as it evaporates, which will keep the soil temperature over 40 degrees-F. 

What is the Difference Between Perennial Ryegrass and Annual Ryegrass?

Despite sharing a name, annual ryegrass and perennial ryegrass are different species of grass. They have various adaptations that give them different characteristics. Unlike perennial ryegrass, annual ryegrass typically lasts for only one growing season and will die out during the hot months. Perennial ryegrass, in contrast, goes dormant during the warm season then comes back to life during the onset of early fall. 

However, both species of grass germinate relatively quickly compared to other kinds of grass. Annual ryegrass will die out during the summer months, leaving more room for different species of grass. Annual ryegrass also usually requires more water than perennial ryegrass as it is adapted to well-drained soil. 

When Should I Plant Perennial Ryegrass?

Since it is a cool-season grass, the best time to plant perennial ryegrass is during the colder months, so early fall. It will establish itself and grow through the winter. If you plant it during the early spring before the summer, it will not have enough time to establish itself before it dries out due to the lack of moisture. Unlike many other grass species, perennial ryegrass does not develop stolons of rhizomes, so its roots do not go very deep. This means that you should not cut perennial ryegrass too short, or else you run the risk of pulling the roots out of the soil.