Perennial Ryegrass and Kentucky Bluegrass are two very popular grass types for cool-season lawns and lawns in the transition zone. Are you thinking about planting one of these types of lawn grass seed on your lawn? Keep scrolling to read my complete Perennial Ryegrass vs Kentucky bluegrass comparison article in which I’ll detail their growth habit, characteristics, germination rate, disease and pest resistance, and more.
By the end of this article you’ll understand which applications each type of grass is best for and be able to choose the best grass for your yard.
In the most brief form possible, the three primary differences between Perennial Ryegrass and Kentucky Bluegrass are:
- Growth Rate – Kentucky Bluegrass takes longer to germinate and establish than Perennial Ryegrass.
- Growth Habit – Kentucky Bluegrass spreads laterally and is better for a thick, full lawn.
- Color – Perennial Ryegrass won’t have the same dark color as Kentucky Bluegrass.
Let’s begin by taking a close look at the characteristics of these turfgrass varieties, including how they differ.
I’ll begin with a short summary of both Perennial Rye and Kentucky Bluegrass.
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About Ryegrass and Using it in a Lawn
Ryegrass is known for its versatility. It’s especially popular in the transition zone.
The transition zone is basically the middle one-third of the United States.
There are several different benefits to using this grass. But it also has some disadvantages.
If you want to grow ryegrass in high humidity regions or outside of its primary zones, your ryegrass will probably end up with disease.
There are two kinds of ryegrass: annual ryegrass and perennial ryegrass, and when shopping for grass seed it’s important to understand the difference between the two and choose the best type of Rye for your seeding application.
What is Perennial Ryegrass?
As you can guess from its name, perennial ryegrass is ryegrass that comes back year after year.
Perennial ryegrass is a cool-season grass.
Like other cool-season grasses, perennial ryegrass has its growth season in the cool months of the year. This is in the spring and fall.
During the summer, Rye spends its energy trying to survive the heat and drought conditions that are less favorable, and won’t grow as much or look as good without significant intervention in the form of irrigation and fertilization.
If you get perennial ryegrass seed for your lawn, be aware that it isn’t quite as hardy in the cold weather as Tall Fescue or Kentucky Bluegrass.
Speed – Its Main Advantage
One advantage it holds over these cool season grass types is that it’s easier to establish from seed – it germinates quickly and matures more rapidly.
If you live in a region where there are cool winters and moderate summers, perennial ryegrass will probably do very well on your lawn.
The Pacific Northwest is an example of a place where perennial ryegrass does especially well. That’s because of the region’s humid and cool weather.
Many homeowners in that region use perennial ryegrass mixed with other grasses or even on its own.
The Place of Ryegrass in the Southern US
Also, many homeowners in southern states use perennial ryegrass for winter overseeding. With warm-season lawns, you have to deal with brown dormant lawns in the winter months, and by overseeding Rye you can have a green lawn year-round (it’ll die out when things warm up again in late spring and your warm season lawn will take over).
Perennial ryegrass germinates very quickly, making it ideal for lawn overseeding projects.
It features quick germination, quite a bit quicker than other kinds of grass seed. Be aware, however, that most varieties don’t spread laterally, and those that do spread slowly once established.
Older types of perennial ryegrass have quite shallow roots as well, meaning they are limited in how well they can deal with drought and heat.
New and improved perennial ryegrass varieties have been developed, however. You will find that some of these do better with difficult conditions.
The Perennial Ryegrass Seed I Use & Recommend
The seeding rate is 8-10 pounds per 1,000 square feet for new lawns and 4-5 pounds per 1,000 square feet for overseeding an existing lawn.
How Kentucky Bluegrass Compares to Perennial Ryegrass
Kentucky bluegrass is a perennial grass variety, and like Perennial Rye it is also a cool-season grass.
In fact, it has the best hardiness for dealing with cold weather out of all popular cool-season grasses used in the United States. Kentucky bluegrass tends to have relatively shallow roots, certainly shallower than Tall Fescue.
Key Differences Between Kentucky Bluegrass and Perennial Ryegrass
A major difference between Kentucky Bluegrass and Perennial Ryegrass is that the former has slower germination. In fact, perennial ryegrass germination will take as little as a third of the time that it takes for Kentucky bluegrass to germinate.
Kentucky bluegrass, however, spreads rapidly once established. It spreads via rhizomes, making it easy for you to achieve a thick lawn, and rewarding those who have the patience and follow-through for a longer seeding project.
Another difference between Kentucky bluegrass and perennial ryegrass is the color. Kentucky bluegrass is famous for its unique deep emerald green color.
It has a distinctive blue tint that makes it one of a kind and very popular with homeowners. Perennial ryegrass has a lighter, more yellowish-green hue.
Think about the type of color you would like on your lawn, and while you can deepen the green color of any lawn with iron applications, if a dark green color is important to you, you may want to choose Kentucky Bluegrass vs Perennial Ryegrass.
The Kentucky Bluegrass Seed I Use & Recommend
The seeding rate I recommend is 3 pounds per 1,000 square feet for new lawns and 1.5 pounds per 1,000 square feet for overseeding an existing lawn.
Why Choose Just One? About Ryegrass and Bluegrass Seed Mixtures
When comparing Perennial Ryegrass vs Kentucky bluegrass, it’s important to understand that these grasses are often used together in mixes, and a good blend of seed may actually be the best choice for your yard.
You’ll frequently find Ryegrass seed added to Kentucky Bluegrass mixes, and Jonathan Green Black Beauty Ultra (the cool season grass seed blend I use and recommend) is actually a mix of elite Fescue, Kentucky Bluegrass and Perennial Rye.
These grass seeds work well together – offering the promise of quick establishment, and long-term durability as the Kentucky Bluegrass overtakes your Perennial Rye.
While Kentucky bluegrass spreads laterally over time, most ryegrass varieties are bunch-type grass species.
By combining different types of seed you can enjoy visible results the first season, and over time your lawn will thicken, with different types of grass becoming dominant in different areas of your yard where light conditions and micro-climates differ.
My Favorite Grass Seed
Patented, Proven, Performance Grass Seed.
Typically seeds combined in these mixtures are chosen for their similarities in color and texture, providing a seamless appearance once they grow in and establish themselves.
Grass Seed Mixtures
Most bags of grass seed contain a variety of different grass seeds. If you get a professional type of grass seed mixture with fescue seed, you will often get five different grass seed types.
This kind of mixture can be useful. After all, if one type of seed in the mixture doesn’t thrive in your region, or in a shady area of your lawn, another kind of seed in the mix will probably do well there.
With good grass seed blends, you have the best chance of achieving a beautiful lawn – even if you’re a beginner.
Exploring Other Cool-Season Grasses You Should Consider
The most popular types of cool-season grasses are
Creeping Bentgrass is a cool-season grass that is used pretty much only on putting greens.
What is Tall Fescue?
Tall fescue is known for its adaptability and ability to thrive in a variety of different conditions. It does well in places designated as “cool/humid” zones of the United States.
This includes most parts of the northern United States.
With tall fescue, you get grass blades of medium width with uniform growth. The leaves are dark green and shiny.
Tall fescue is able to deal with extreme temperatures, as well as strong tolerance to general wear and tear.
It tolerates shade, drought, and heat, and it isn’t susceptible to disease. This is one reason why this grass seed is so popular.
This grass grows through a bunch-forming mechanism. The individual grass shoots (or tillers) that emerge from the plant’s base are what let it spread.
Pros & Cons of Tall Fescue vs Bluegrass & Ryegrass
An advantage of this is that you probably won’t have to dethatch it very often, and you should find it quite easy to stop it getting into your garden beds. A disadvantage is that the grass isn’t able to effectively self-repair.
One disadvantage of tall fescue is the fact that it’s prone to developing brown patch disease. This is especially a risk if you live in a place that is humid and hot.
It may also develop snow mold disease in cold and wet months of the early spring. With this latter problem, however, it begins doing well again once the weather gets warmer.
Tall fescue is especially popular for homeowners in the transition zone of the United States. It has a deep root system, meaning it can easily withstand heat and drought.
It’s common to find tall fescue in cool-season grass seed mixtures.
You should usually mow your tall fescue tall (as the name implies). I like to keep mine about 3 inches or taller. Of course, the exact height you should keep your grass will depend on the blend that you get.
Check the instructions on the seed bag label.
When to Consider Fine Fescue
Fine fescue is a fast-growing grass species. This kind of grass has a grayish green color, and it can do very well in shade.
There are some different kinds of fine fescue available, including hard fescue, creeping red fescue, chewings fescue, and sheep fescue. Of course, not all of these will be suitable for a homeowner’s lawn.
Fine fescue does well in cold weather. It’s so hardy that many homeowners use it for overseeding and filling in spaces where they have trouble growing grass.
If you have a heatwave in your area, just make sure to water your fine fescue more often. Fine fescue could be a good choice if you have high foot traffic on your lawn.
Tall Fescue vs Kentucky Bluegrass vs Perennial Ryegrass
Let’s view a quick comparison chart to help you better understand the differences between Kentucky Bluegrass, Perennial Ryegrass, and Tall Fescue.
|Fast Growth Rate
|Slow Growth Rate
|Extremely Fast Growth
|Strong Foot Traffic Tolerance
|Strong Foot Traffic Tolerance
|Excellent Foot Traffic Tolerance
|Above-Average Drought Tolerance
|Mid-Range Drought Tolerance
|Mid-Range Drought Tolerance
|Dense Shade to Full Sun
|Partial Shade to Full Sun
|Partial Shade to Full Sun
Perennial Ryegrass and Kentucky Bluegrass Work Well Together
Perennial ryegrass and Kentucky bluegrass are often combined together in cool-season grass seed mixtures. Consider getting this kind of mix if you want the advantages of both types of grass in your lawn.
Perennial ryegrass is renowned for its fast germination, while Kentucky bluegrass is strong in how quickly it spreads and its striking color.
No matter what kind of cool-season grass seed or grass seed blend you get, remember to properly maintain your lawn.
Keep your lawn appropriately watered and fertilized. Remember to do aeration and overseeding, too.
I hope this perennial ryegrass vs Kentucky bluegrass comparison helps you understand these grass types and how they can work together on your lawn.
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