When it comes to experts on lawns, University of Maryland’s Chuck Schuster is a cut above. Not only is he an educator in commercial horticulture, but he also consults on grass with many nursery, greenhouse, turf and garden center industries. And in his spare time, he provides guidance on turf protection to some of the largest stadiums and sports complexes in the Washington, DC area.
I was lucky to have Schuster educate me recently on the differences between cool and warm season grasses and how to build the perfect lawn.
COOL SEASON GRASSES
As a rule, most lawns grown in the mid Atlantic region consist of cool season grasses. These include fescue, bluegrass and ryegrass, all of which go dormant in January and February. But in early March, when temperatures climb above 32°F, these grasses become active. And from March to June, they are actively growing, with 60 percent of their top growth occurring in the first six weeks they break dormancy.
Cool season grasses put on 60% of their top growth from March to June.
In late June and July, however, when temperatures reach 85° F and above, cool season grasses undergo what Schuster terms the ‘Summer Slump.’ During this period, they don’t actively grow. As a result, they often turn brown.
Cool season grasses often turn brown during the ‘Summer Slump’.
Cool season grasses turn green again (resuming growth), once temperatures cool and soil moisture is replenished. This usually occurs in September, when they also begin developing roots for the winter. In fact, cool season grasses will continue growing underground all the way through December until the soil freezes.
Cool season grasses will continue growing until the soil freezes.
WARM SEASON GRASSES
Warm season grasses, on the other hand, prefer drier soils and have a high tolerance for drought. The most common of these are zoysia and Bermuda grass. These varieties tend to handle heavy traffic better and can tolerate closer mowing. In fact, Bermuda grass’s high resiliency and ability to heal itself quickly make it one of the top choices for many sports complexes.
“Warm season grasses are so resilient they’ll even creep over asphalt,” says Schuster.
Bermuda grass lawn
The downside for homeowners is that Bermuda grass and zoysia lawns turn brown when they go dormant, which usually occurs once temperatures dip below 50° F. On the East Coast, this isn’t the best look for a perfect lawn. Growth begins again when temperatures rise in the spring, with warm season grasses experiencing active growth from April through September.
Warm season grasses go dormant in the winter.
WHY YOU NEED TO KNOW THE DIFFERENCE
Why care what type of grass you have? Because, according to Schuster, understanding what type of turf you have determines its care. Building a perfect lawn involves controlling for mowing height, water needs and perhaps most importantly, fertilization requirements.
Before doing anything to your lawn (especially fertilization) determine whether you are working with cool or warm season grass!
THINGS THAT BUILD A PERFECT LAWN
According to Schuster, these are the five building blocks that go into making a great lawn.
- Good soil
- Adequate moisture
- Proper mowing height
- Yearly aeration
- Proper fertilization
Maintaining soil pH in an optimum range helps lawns absorb nutrients properly. Moreover, it reduces the threat from diseases and weeds. Generally a soil pH of 5.8 to 6.4 is considered ideal. Depending on your grass species, turf problems may start to occur when your soil pH is either above 7.8 or below 5.6,
To mitigate this problem, Schuster recommends doing a soil test to determine your soil pH before applying nutrients.
Determine your soil pH first before applying nutrients.
According to the Lawn Institute, most lawns grow best with a maximum total of one inch (2.5 cm) of water a week. This amount can come from rain or irrigation, or a combination of both. This will saturate the underlying soil to a depth of 4 to 6 inches (10 to 15 cm), allowing the roots to create a ‘soil-water bank’ to draw moisture from during periods of hot weather and drought.
Proper irrigation helps your lawn develop deep, strong roots.
PROPER LAWN MOWING HEIGHTS (Hint: Mow High)
Longer grass helps shade out weeds and keeps the soil cooler. Schuster recommends mowing cool season grasses a little higher, at 3- 3 ½ inches. This keeps grass greener in the summer and reduces thatch. Mow when the lawn is dry, removing no more than 1/3 of the height.
Warm season grasses, on the other hand, can be mown close to the ground due to their high resiliency and preference for drier soil.
Mow cool season grasses high to shade out weeds and diseases.
Either way, don’t forget to sharpen your blades once a year. Dull mower blades tear the grass blades, increasing the chances of disease and leaving a brown tint on the lawn.
Aeration helps a lawn maintain its health and vigor. It also reduces maintenance requirements by improving air exchange between soil and atmosphere while facilitating water and fertilizer uptake. Perhaps most importantly, it improves root development by reducing soil compaction. This in turn helps a lawn battle heat and drought better.
It also accelerates thatch break down.
According to Schuster, every good lawn benefits from a good aeration. It can be done in spring or fall. However, never aerate when the lawn is dried out or too wet, it will tear up the ground.
Spring fertilization encourages top growth (and mowing) at the expense of root growth. It produces lush turf, but it also makes a lawn more susceptible to insects and disease. Depriving the roots of proper development increases risk during dry times in the late summer.
Fertilize cool season grasses in the fall for optimum root growth.
On the other hand, when you fertilize a lawn in the fall, the nutrients go mainly towards root growth. And healthy roots mean healthy plants. Grasses build a reserve to help survive the winter and start out strong in the spring.
“It’s the best bang for your nutrient dollar,” says Schuster.
BONUS: LEAVE THE CLIPPINGS ON YOUR LAWN
Who doesn’t like free fertilizer? Leave the clippings on the lawn to put nitrogen back into the turf. It bears noting that soil amendments like LeafGro are simply products made from our own discarded leaves and grass (and sold back to us by nurseries.)
Glass clippings return nutrients to the soil and contribute to healthy turf.
Grass clippings contribute to healthy turf by returning nutrients to the soil in a slow-release form. In fact, returning grass clippings to the lawn ‘credits’ it with as much as one pound of nitrogen per year, says Schuster.
To build a perfect lawn, make sure to do the following:
Figure out what type of turf you have.
Do a soil test to determine pH needs.
Fertilize at the optimum time.
Mow at a height to benefit the lawn, not the weeds.
Aerate once a year to build strong and healthy roots.
And enjoy your lawn!
Our family dog, Winston, enjoying our cool-season lawn.