All You Need to Know About Kentucky Bluegrass

Kentucky Bluegrass Sod
For many lawn owners in the United States, Kentucky bluegrass is synonymous with the ideal lawn. When given its preferred growing conditions and proper care, this grass produces a dense, lush, durable lawn that lives up to its reputation. However, Kentucky bluegrass doesn't do it on its own. This grass requires a relatively high level of maintenance to look its best, but results can be worth it. Depending on your grass growing region and your lawn care goals, Kentucky bluegrass may be a perfect choice for you.

Kentucky Bluegrass at a Glance

  • Cool-season lawn grass
  • Suitable for northern lawns from coast to coast.
  • Excellent winter hardiness
  • Some varieties susceptible to heat and drought.
  • Limited shade tolerance
  • Some varieties vulnerable to stress damage.
Black fence
Kentucky bluegrass gained early U.S. popularity as a pasture grass in Kentucky.

Kentucky Bluegrass Basics

The state of Kentucky lays claim to the nickname “Bluegrass State," but Kentucky bluegrass didn't originate there. Like many common U.S. turf grasses, this versatile, widely used grass is native to Europe and northern Asia.1 Its first use in the U.S. came as a pasture grass in states like Kentucky, where it still covers the state's gently rolling hills. Often referred to in the grass industry by the initials KBG, Kentucky bluegrass rose to become a premier lawn grass throughout much of the country.

Kentucky bluegrass is what's known as a perennial, cool-season lawn grass. This means it comes back year after year and grows most vigorously during the cool seasons of fall and spring. KBG has the greatest cold hardiness of all the common cool-season lawn grasses.3 It's used most extensively in northern climates where moderately warm summers and cold winters align with its natural preferences and growth cycle.

Compared to tall fescue, traditional Kentucky bluegrass varieties have relatively shallow roots, which typically lead to lower tolerances for heat and drought. Historically, this has restricted the widespread use of KBG south of the challenging transition zone, where higher heat and humidity favor warm-season grasses, such as Zoysia grass. Even so, KBG admirers in warmer areas aren't easily deterred. It's not uncommon to find heavily irrigated Kentucky bluegrass growing in sun-baked lawns of the West and Southwest.

Green grass in sunlight
Kentucky bluegrass blades have distinctive, boat-like tips.

Additional Characteristics to Consider

Kentucky bluegrass establishes easily from seed, but it germinates more slowly than some other cool-season grasses. Fast-growing perennial ryegrass, for example, germinates in one-third the time of KBG. Unlike bunch-forming grasses, such as tall fescue and ryegrass, Kentucky bluegrass is a self-spreading, sod-forming grass. Once established, it spreads readily via underground stems (known as rhizomes) to form a dense, thick turf. This aggressive growth habit gives KBG the capacity to recuperate quickly from damage.

Part of the charm of a healthy Kentucky bluegrass lawn is its rich emerald to blue-green color. Add to that its medium to fine texture, and a KBG lawn is both beautiful to look at and comfortable for bare feet. As with other cool-season grasses, Kentucky bluegrass growth slows significantly during hot summer months. During extreme heat or extended drought, the grass will go dormant. However, it recovers quickly with irrigation and a return to normal conditions.

Kentucky bluegrass prefers full sun, but some varieties can do well in lightly shaded areas. Look on the seed tag label of many grass seed mixes, including shade and sun & shade mixes, and you'll find KBG varieties mixed with other cool-season grasses. Fast-greening perennial ryegrass and shade-tolerant fescues complement Kentucky bluegrass's strengths to create versatile, lush, cool-season lawns. Durable KBG is also a regular component of seed mixes for athletic fields.
Field of Kentucky bluegrass
Well-maintained Kentucky bluegrass develops into thick, lush lawn.

Kentucky Bluegrass Lawn Care

With Kentucky bluegrass and other cool-season lawn grasses, the best time to plant seed and do major lawn maintenance is during early fall, as KBG growth peaks. Because of KBG's rhizomatous growth, the grass develops thatch easily, which can add to drought stress and potential for disease. Depending on your mowing and care practices, your KBG lawn may need dethatching every year or two.

Wise water management is essential for Kentucky bluegrass lawns. Deep, thorough irrigation helps encourage deep root growth, while shallow, frequent watering discourages it. During normal weather, a typical KBG lawn needs at least 1 inch of water weekly from irrigation or rainfall. During warmer weather and in the transition zone, 2 inches or more per week may be needed.1 While the relatively shallow roots of traditional KBG varieties historically required more water than tall fescue or most warm-season counterparts in similar situations, modern developments have greatly improved water efficiency.

Premium, water-conserving seed such as Pennington Smart Seed Kentucky Bluegrass can add to your lawn's resilience. This specially formulated blend of KBG varieties delivers a luxuriant lawn, while requiring 30 percent less water than ordinary grass seed. Improved varieties, such as the award-winning 'Mallard' Elite Kentucky bluegrass, developed through Pennington-affiliated research and breeding programs, build on KBG strengths with improved drought tolerance, richer color, and dense, durable, compact growth that translates to lower maintenance needs.

Poa pratensis (Kentucky bluegrass)
When allowed to flower, Kentucky bluegrass has a panicle-like seed head.
Like other cool-season grasses, Kentucky bluegrass should be mowed higher than warm-season grasses. Warm-season Bermudagrass, for example, is routinely kept near 1 inch tall, but KBG should be mowed to 2 to 2 1/2 inches high. During periods of high heat and lower rainfall, recommended KBG mowing heights increase to 3 to 4 inches.

Kentucky bluegrass lawns typically require more fertilizer than tall fescue and other grasses. In alkaline soils, blades can lose their rich green color due to pH-induced iron deficiency. The optimal soil pH for KBG lawns is near 5.8 to 7.0.2 Regular soil testing every three to four years can help you maintain a healthy pH balance and rich KBG color with the help of quality lawn fertilizers, soil amendments and mineral supplements such as Ironite Mineral Supplement 1-0-1-by Pennington./sup>.

When your lawn goals call for a dense, durable, cool-season lawn with luxuriant color, Kentucky bluegrass may be the answer to your hopes. Pennington is committed to growing the finest grass seed possible and providing you with premium lawn and garden products, timely email tips, and educational resources to help you and your lawn grow.

Pennington and Smart Seed are registered trademarks of Pennington Seed, Inc.

Ironite is a trademark of Central Garden & Pet Company.


Sources:

1. Duble, R.L., “Kentucky Bluegrass," Texas A&M Agrilife Extension.

2. Patton, A. and Boyd J., “Choosing a Grass for Arkansas Lawns," University of Arkansas Cooperative Extension.

3. Cook, T., “Kentucky Bluegrass, Poa Pratensis L.," Oregon State University Department of Horticulture.
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