Looking at a perennial ryegrass lawn next to a sample of Kentucky bluegrass, cut to the same height, you might not see a big difference. Sure, perennial rye is a little lighter in color and the blades of Kentucky bluegrass are a little thicker, but, on the surface, they almost seem interchangeable.
That’s why, in the article below, you’ll learn that the biggest difference between Kentucky bluegrass and perennial ryegrass is below the surface and I’ll explain how it can make a huge difference in how your lawn performs all year-round.
Comparing Perennial Ryegrass vs Kentucky Bluegrass
There is more than one difference between perennial ryegrass and Kentucky bluegrass, but they have quite a few similarities, too. Neither of these grass types is a bad choice for a lawn but knowing how each type works and what needs they have can help you decide if either perennial ryegrass or Kentucky bluegrass would be a bad choice for your lawn and your specific lawn goals.
Appearance
Perennial ryegrass is a bright green grass with a fine texture. It has a clumping habit and will stretch out stolons under the ground so it can spread. This fine texture and tight-knit though shallow root system makes perennial rye an ideal choice for seeding over an existing lawn during warm winters or as a year-round choice in colder climates.
Kentucky bluegrass, also known as meadow grass, has a dark green color and a fine though slightly thicker blade type than perennial ryegrass. Kentucky bluegrass is fast growing and grows in tight-knit clumps spawned through the production of rhizomes. If well-maintained and cut short, Kentucky bluegrass does, however, tend to quickly accumulate thatch.
Best Uses for Perennial Ryegrass and Kentucky Bluegrass
Perennial ryegrass is a great turfgrass to use in low-traffic areas and in places where pets are unlikely to go. Though attractive in appearance and texture, perennial ryegrass is a bit delicate and has a shallow root system. It is not meant for high-traffic areas or, in hotter climates, long-term use. Due to this, perennial rye is often used to seed over a short, dormant grass during hot winters. Annual ryegrass, a close relative to perennial ryegrass, provides these same benefits to northern temporary turfgrass installations.
Kentucky bluegrass is a great cultivar for those looking for a lawn that can be cut short, that has an easy time crowding out weeds, and that has a fast recovery time. This is why Kentucky bluegrass is one of the primary grass types found on golf courses.
Soil Types and pH Needs of Perennial Ryegrass and Kentucky Bluegrass
Perennial ryegrass likes dry, well-drained soil and can easily shift out of place or become infested with mold and mildew if water is allowed to sit on it or the ground becomes muddy. Before planting, the soil should also be loosened as perennial ryegrass does not spread easily in compacted soil and may avoid certain compacted patches altogether. A pH of 5.5 to 7.5 is ideal for perennial ryegrass.
Kentucky bluegrass is far less comfortable than many turfgrass types in acidic soil. To do its best, Kentucky bluegrass should be planted in soil that has a pH of 6 to 7, erring on the alkaline side is better if possible. The soil should be well-drained and moist. Kentucky bluegrass can tolerate more muddy conditions and is much more likely to hold in place.
Water Needs for Perennial Ryegrass and Kentucky Bluegrass
Perennial ryegrass requires only 1” of water per week. This is about average for most turfgrass species. Too much water is more of a problem for perennial ryegrass than too little as this variety is easily affected by mold, mildew, and algae growth.
Kentucky bluegrass requires slightly more water than average with a weekly recommended water application of 1.25” to 1.5”. Kentucky bluegrass can handle some standing water and is far less likely to become displaced if conditions are muddy than perennial ryegrass.
Sun, Shade, and Temperature Requirements for Perennial Ryegrass and Kentucky Bluegrass
Perennial ryegrass requires full sun but can tolerate intermittent shade. If left in the shade, perennial rye should require slightly less water to maintain optimal moisture conditions. Perennial ryegrass grows best in cool temperatures and will go dormant if temperatures fall below 55F or rise above 85F.
Kentucky bluegrass will go dormant if temperatures fall below 50F or rise above 80F. The ideal growing temperature for Kentucky bluegrass is about 70F. If seeding a new Kentucky bluegrass lawn, it’s recommended that sowing is down as soon as average temperatures reach about 58 to 60F as this will allow the seedlings to establish as quickly as possible. Full sun exposure is recommended for Kentucky bluegrass, though it can tolerate partial sun or shade.
Durability of Perennial Ryegrass vs Kentucky Bluegrass Lawns
Perennial ryegrass has a shallow root system and is susceptible to taking on too much moisture. It is quick to fill in gaps or damaged spots and grows quickly. However, it is also susceptible to damage from average traffic, digging animals, and pets.
Kentucky bluegrass has a strong, thick root system and tougher blades than perennial ryegrass. However, it is slow to fill in gaps or “bald” spots and slow to establish itself as a new lawn. This could be the key difference between perennial ryegrass and Kentucky bluegrass.
Common Pests and Diseases for Perennial Ryegrass Lawns and Kentucky Bluegrass Lawns
Perennial ryegrass and Kentucky bluegrass, like most turfgrasses, are equally susceptible to insect damage from common species like grubs, ants, and thrips. Perennial ryegrass is more likely to be damaged by mold, mildew, and digging animals. Kentucky bluegrass is better at recovering from mole and vole damage over the long run but is slow to do so. Geese are also attracted to Kentucky bluegrass lawns (although there are ways to keep geese off your lawn).
Mowing Needs of Perennial Ryegrass and Kentucky Bluegrass Lawns
Perennial ryegrass is best kept at a height of 2”. It should be mown once a week in cooler seasons and, above 85F, may not need to be mown at all.
Kentucky bluegrass has a similar growth habit and, if kept at a height of 2 to 3” should only be mown once a week. If it is kept at 1”, mowing twice a week to maintain an even height may be necessary. If kept this short, Kentucky bluegrass lawns will also need to be dethatched several times a year.
Can You Mix Kentucky Bluegrass with Perennial Ryegrass?
Perennial ryegrass should not be mixed with Kentucky bluegrass. Perennial ryegrass is quick to establish while Kentucky bluegrass is slow to become established. Within the first few weeks of seeding, the perennial ryegrass may crowd out the Kentucky bluegrass seedlings and prevent them from becoming established enough to survive.
However, annual ryegrass can be mixed with Kentucky bluegrass for seeding. The annual ryegrass should be added in half as much as the Kentucky bluegrass. Over the winter, the annual ryegrass will die off, allowing the Kentucky bluegrass to completely colonize the lawn during the following spring.
Types of Grass Related to Perennial Ryegrass
Perennial ryegrass is the long-lasting counterpart to the more tropical annual ryegrass. Other than temperature needs, both of these types of ryegrass have similar appearances, water needs, light needs, and growing habits.
Types of Grass Related to Kentucky Bluegrass
Kentucky bluegrass is available in more than 200 specialized strains. There are many strains as this is such a popular turfgrass variety for golf courses and athletic fields. Whether you need a strain that can handle slightly higher temperatures or that resists a particular lawn ailment, there are strains available to help you overcome these issues.
The Best-Case-Scenario for a Perennial Ryegrass or Kentucky Bluegrass Lawn
Perennial ryegrass is best used in low-traffic areas where a lawn needs to be established quickly. Ideally, this area has excellent drainage and plenty of sunlight. Its shallow roots and fine-bladed nature make it an excellent choice for an area that may be converted into something else in the following year or two as it is an easy grass to remove.
Kentucky bluegrass is a great choice for high-traffic lawns or low-maintenance lawns that will be cut short for appearance or utility. This variety also requires a lot of sun, but it can handle wet conditions, soil compaction, and a host of other soil ailments- as long as the pH isn’t too acidic.
Quick Summary of Perennial Ryegrass vs Kentucky Bluegrass
Below I’ve put together a table summarizing all of the key information relating to each of these turf types, so you can compare them very quickly.
| Grass Type | Perennial Ryegrass | Kentucky Bluegrass |
|---|---|---|
| Appearance | Bright Green with Smooth, Fine Blades | Dark Green with Plump, Fine Blades |
| Popular Uses | Winter Overseeding in Warm Climates or Low-Water Lawns and Pasture | Golf Courses and Athletic Fields, Roadsides |
| Ideal Soil Type and pH | Dry and Well-Drained Soil is Ideal - 5.5 to 7.5 Ideal pH | Well-Drained to Moist – 6 to 7 Ideal pH |
| Water Requirements | 1” of Water Per Week – Average Overall Water Consumption | 1.25 to 1.5” of Water Per Week – Slightly Above Average Water Consumption |
| Sun/Shade/Temperature Needs | Full Sun Preferred/Dormant at 55F | Full Sun Preferred/Dormant Below 50F and Above 80F |
| Durability | Low-Average Durability and Damage Recovery | High Durability, Fast Recovery |
| Pests and Diseases | Mold, Mildew, Moss, and Algae if Too Moist – Webworms, Thrips, Grubs – Digging Animals | Geese, Digging Animals – Ants/Webworms/Thrips/Grubs – Spore-Based Diseases |
| Mowing Needs | Should Be Mown to 2” Height – Grows Best in Cool Weather | Can Be Mown to 1” or Less – 2 to 3” Height Average – Grows Best in Cool Weather |
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