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What Is a Grassy Weed?

Jun 21, 2024

These Weeds May Look Like Turfgrass, but You Don’t Want Them Popping up in Your Lawn

While some flowering broadleaf weeds, like dandelions, are fairly easy to spot in your lawn, other varieties of weeds might seem more akin to turfgrass at first glance – but that doesn’t mean you want them in your lawn!


In general, the most common weeds plaguing North American lawns can be grouped into three categories: grassy weeds, broadleaf weeds, and sedges. Grassy weeds (like crabgrass), broadleaf weeds (like dandelions and clover), and sedges (like nutsedge) look and behave very differently, which means the methods used to control them will differ as well.


Last month, we took a closer look at broadleaf weeds. Today we’re diving into grassy weeds – and what to do about them!

Characteristics of Grassy Weeds

As the name suggests, undesirable “grassy“ weeds share many characteristics with more desirable turfgrass, including long, flat, pointed green leaves (or “blades”), like blades of grass. However, you’ll be able to spot a few key differences. Grassy weeds may grow in clumps or bunches, with a taller or quicker growth rate than the surrounding lawn, prominent seed heads, prolific seed production, and brighter or darker coloring than regular turfgrass.


Despite similar appearance to turfgrass, grassy weeds pose a threat to home lawns. These aggressive growers can out-compete your lawn for nutrients, water, and sunlight, weakening the turf and making it more susceptible to threats, like disease, pests, and other weeds. 

Identifying Grassy Weeds

You’ll recognize these characteristics in in many common lawn weeds, including: 


  • Crabgrass: Crabgrass is a troublesome annual weed that resembles a miniature corn plant. It forms coarse clumps low to the ground, spreading in hot, dry areas like driveway edges and full sun zones. Often confused with other grassy weeds, crabgrass is undesirable due to its weak structure, coarse texture, and unsightly color, crabgrass spreads quickly, potentially choking out desirable grasses. Once crabgrass is established, it will take years to manage.

  • Quackgrass: Quackgrass is characterized by its vigorous rhizomatous growth, allowing it to spread quickly and aggressively in a variety of soil types and climates. Known for its tough, creeping underground stems, rhizomes, and long, flat, pointed leaves, quackgrass competes with desirable crops or plants for nutrients, sunlight, and water. Quackgrass is very resilient and persistent, able to regenerate from small root fragments, making it difficult to combat.

  • Annual Bluegrass: Annual bluegrass (commonly known as poa annua or simply poa) is a grassy weed so prevalent that nearly every lawn harbors some poa, with some lawns succumbing entirely to its presence, while others display scattered or unsightly patches. Annual bluegrass is undesirable because of its pale green color, prominent seed heads, and vulnerability to summer heat stress that can leave lawns sparse and feeble. 

  • Tall Fescue: Tall fescue is an aggressive perennial with thick underground rhizomes.  It is characterized by its tall, coarse and bunch-forming habit, with the mature plants reaching heights of up to 3 or 4 feet. Tall fescue is resilient and tolerant to a range of environmental conditions, including drought and poor soil quality, which makes it a versatile and robust option for various agricultural and landscaping purposes, but far less desirable for lawns, which require a finer, more manicured appearance. Once established, it’s extremely difficult to eradicate tall fescue.

  • Common Bermudagrass: Common bermudagrass is a robust, stoloniferous grassy weed that can swiftly infiltrate lawns under well irrigated conditions. Its prolific seed production, invasive nature, and deep rhizomes make it resilient and difficult to eradicate. In southern regions of the United States, these characteristics actually make common Bermudagrass a suitable grass variety for warm-season lawns. However, it’s much less suitable in cooler climates, due to its aggressive nature and unsightly winter dormancy.


Weedy Grass

Controlling Grassy Weeds

Once established, grassy weeds are extremely difficult to control. If left unattended, they can spread quickly, stealing valuable nutrients from your turfgrass lawn, so it’s important to start addressing grassy weeds as soon as possible. Different control methods are required for grassy weeds, such as crabgrass, than are needed for other types of weeds, like broadleaf weeds and sedges. Contact your local Weed Man for recommendations and solutions that are suitable to improve the conditions of your lawn.


Unfortunately, in some cases, the only control methods for grassy weeds may be to improve the overall health of your lawn with strategic cultural practices, helping it withstand grassy weeds and other lawn conditions.

A Healthy Lawn is the Best Defense

A thick, healthy, well-maintained lawn is always the best line of defense against weeds and other harmful lawn conditions, like disease and pests. In addition to your weed control program, a healthy lawn can be achieved through beneficial cultural practices, which include:

  • Core Aeration: Aerating your lawn can improve soil drainage and help reduce the likelihood of lawn diseases. This will also alleviate soil compaction and allow water and nutrients to penetrate deeper into the soil.

  • Fertilization: Regular applications of Weed Man’s specially formulated, slow-release granular fertilizer will help provide your lawn with adequate nutrients. These applications are timed specifically to avoid over fertilizing the lawn.

  • Watering: Under normal circumstances, you should be watering your lawn a few times per week for 30-45 minutes in each area. During hot and dry periods, most lawns should be watered as much as required to maintain its desired green color. Always water in the early morning so the turf has time to dry by nightfall.

  • Mowing: Maintain a regular mowing schedule with a razor sharp blade. Never remove more than a ⅓ of the grass blade at each mowing.


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