Given its name, one would assume that this herbaceous, cool-season turfgrass is native to the United States. But that is not the case. Kentucky bluegrass is indigenous to nearly every country in Europe, as well as parts of North Asia and Morocco.
Its seeds were brought to the United States by Spanish explorers. It became a valuable pasture plant where the climate allowed it to grow. It was soon added to lawns and parks. Its most well-known location is at historic Lambeau Field, home of the Green Bay Packers.
Even if you don’t want a lawn as impressive as this famous football field, Kentucky bluegrass can be a valuable addition to your yard. So, in this article, we will go over how to properly care for it.
It’s a common misconception that Kentucky bluegrass (Poa pratensis) got its name from the popular music genre in that part of the country. It gets its name from the blue flower heads it produces when allowed to grow.
The perennial cool-season grass comes in two varieties, which are further subdivided into undefined subspecies:
Both varieties have dark green leaves that can reach 8 inches in length. They are 1 to 2 tenths of an inch wide and have boat-shaped tips. Their texture varies from smooth to rough.
Between May and July, the plant blooms for a relatively short time. Flowers appear on a cone-shaped panicle that grows from the basal whorls.
This cool-season plant’s root system spreads underground via rhizomes. It can self-repair when it is worn thin, damaged, or injured. As its root system spreads, dense mats form on the surface. The mats are reasonably durable and can withstand moderate to heavy traffic.
Kentucky bluegrass prefers full sun, but it can tolerate some shade. It grows best in the fall, winter, and spring before the temperatures rise too high. During the summer, its growth will slow. If your lawn becomes stressed in hot weather, it may go dormant to protect itself.
Although it is not as hardy in hot weather, this plant has the highest cold-weather hardiness of any cool-season grass. It is entirely possible that it will never go dormant if the winter weather is only moderately cold and the summer months are not excessively hot.
Seed companies have started combining Kentucky bluegrass with perennial ryegrass and certain fescues. These varieties are popular among both professional and amateur gardeners due to their ability to develop color quickly and tolerate shade. Because they complement each other so well, these mixes combine to form what could be considered the perfect hybrid grass.
To a point, Kentucky bluegrass is drought-tolerant. You should provide irrigation if it goes dormant during the summer due to high temperatures and a lack of water.
During normal weather conditions, your lawn requires at least 1 inch of water per week, either naturally or through irrigation.
During hotter weather, your lawn may require 2 inches of water per week to thrive. If temperatures remain consistently above 95°F, it may require 3 inches of water per week to avoid dormancy.
Watering Kentucky bluegrass frequently and shallowly will not benefit it. This method of watering discourages roots from growing deeply into the soil. Water less frequently but for longer periods of time instead. This promotes deeper root growth, which results in a tougher, more resilient, and healthier turf.
Early in the morning is the best time to water your lawn. Cooler temperatures at that time of day reduce evaporation. Water that collects on the leaves will have time to fall to the ground and reach the soil.
Fertilizing is essential no matter what type of plant you have. However, with Kentucky bluegrass, it can mean the difference between a lawn that is the envy of the neighborhood and a lawn that attracts unwanted attention.
Depending on the state of your Kentucky bluegrass, it may require 3 to 4 fertilizer applications to thrive. This particular perennial is fertilized in a holistic manner. As a result, each application employs a different fertilizer to achieve the desired results. If done correctly, this ensures a strong, virile, and overall healthy turf.
To distribute the product on your lawn, use a rotary-style spreader for all applications. Spread your fertilizer by walking vertically the first time and horizontally the second. This method will completely cover the area and produce the healthiest, best-fed Kentucky bluegrass.
First Application: Early Fall
You’ll apply your first round of fertilizer in the first three weeks of September, depending on the weather where you live. If you live in a part of the country where it is still hot at this time of year, you should delay applying fertilizer until temperatures begin to cool.
Use a fertilizer with a balanced NPK ratio of 10-10-10. This application is intended to supplement the soil and aid in the repair of any residual stress left over from the hottest months of the year.
Second Application: Late Fall
The second application will take place between the last week of October and the first half of November, depending on your climate. This round should be applied before it becomes too cold for the roots to absorb the nutrients.
This application is designed to promote healthy root development. As a result, you’ll need a nitrogen-rich fertilizer. A high-quality product with an NPK ratio of 32-3-8 or 24-4-12 will be most effective. To determine how much fertilizer to use, follow the instructions on the package.
If at all possible, use a product that contains slow-release nitrogen. The risk of burning the leaf blades is reduced by using a slow-release product. It also provides nutrients to the plant over a long period of time. This promotes healthier growth and allows the roots to become stronger as they spread.
Third Application: Mid-Spring
The third round of fertilizer should be applied in late March or early April.
This variety is susceptible to crabgrass infestation because it slows its growth in the summer. To avoid this, use a weed and feed product. In addition to preventing crabgrass spread, this fertilizer will strengthen your lawn and reduce the likelihood of it going dormant due to heat stress.
A standard bag of weed and feed contains enough product to cover 5,000 square feet. The majority are also reasonably priced.
Apply this fertilizer just before it rains for best results. If no precipitation is forecast, water the product into the soil yourself to ensure that it reaches the roots. If the fertilizer isn’t absorbed into the soil, you’ve squandered your time and money.
Fourth Application: Late Spring
The timing of the fourth round of fertilizer is determined by the plant’s color. If your Kentucky bluegrass becomes stressed as temperatures rise in late spring, it may begin to lose some of its rich, deep green hues.
If you notice that your lawn is turning yellow, it’s time to add more plant food.
Choose an organic product that will not burn up the blades to reduce the risk of damaging your turf. Several market products will suffice. Instead of caustic inorganic chemicals, look for one that uses processed animal manure or worm castings. Slow-release products should have a balanced NPK ratio of 10-10-10 or 5-5-5.
Skip this application if your lawn shows no signs of heat stress or fading color. Over fertilization can be harmful to healthy plants.
One golden rule of mowing any lawn is to only remove the top third of the blade. Kentucky bluegrass is no exception. Removing more than the top third of the plant may result in the plants being scalped. It also has a negative impact on the root system.
This variety should be kept between 2 and 2.5 inches tall. This is higher than the warm-season equivalents.
During the summer months, when temperatures rise and the risk of drought increases, keep the lawn between 3 and 4 inches tall. This will keep weeds at bay after the plant has slowed its growth rate. Keeping the grass tall keeps sunlight from reaching the soil, preventing weed seeds from germinating.
Kentucky bluegrass grows slowly in comparison to most other cool- and warm-season grasses. You will not have to mow as frequently as you would otherwise. Make your mowing schedule based on the growth rate of the grass rather than a strict timetable. Mowing the grass too frequently can harm it and wear it down.
You might want to try grass cycling with this plant. Not only are clippings high in micro- and macronutrients, but they are also high in water. Leaving grass clippings on your lawn can be beneficial as long as they aren’t soaked and clumping.
Fungal diseases such as powdery mildew, rust, and leaf spot can cause problems for Kentucky bluegrass. All of these things can be difficult to notice. Unfortunately, once your lawn is infected, the damage is done, and you must wait to see if there are any long-term consequences.
Fungal diseases frequently manifest as brown or damaged patches. If you notice anything like this, don’t spray your entire yard with fungicide. Wait a few days to see if that patch spreads out concentrically around the original patch.
If the patch spreads, spray the infected area with a fungicidal product that is safe for your specific grass variety.
Excessive moisture exacerbates diseases like leaf spot. Use proper watering techniques and follow a morning watering schedule. This prevents moisture from accumulating and creating ideal conditions for the spread of leaf spot.