Crabgrass Vs Johnson Grass: A Comparative Guide

Are you tired of battling unwanted grasses in your lawn? If so, you’ve likely come across the dilemma of crabgrass vs Johnson grass. Don’t worry, we’ve got you covered! In this article, we’ll delve into the key differences between these two grasses and provide you with effective solutions to keep your lawn looking pristine. So, whether you’re a seasoned gardener or just starting out, this introduction will set the stage for an informative and engaging discussion on crabgrass vs Johnson grass. Let’s dive in!

Crabgrass vs Johnson Grass: A Comparative Guide

Crabgrass vs Johnson Grass: A Detailed Comparison


Crabgrass and Johnson grass are two common types of weeds that can invade lawns and gardens. They both have the potential to cause damage and reduce the aesthetic appeal of your outdoor spaces. Understanding the differences between these two types of grasses is crucial in order to effectively manage and control them. In this article, we will delve into the characteristics, growth patterns, control methods, and potential impacts of crabgrass and Johnson grass.

Characteristics of Crabgrass

Crabgrass, scientifically known as Digitaria, is an annual grass that belongs to the Poaceae family. It is a warm-season grass that thrives in hot and dry conditions, often emerging in late spring or early summer. Some key characteristics of crabgrass include:

  • Low-growing: Crabgrass typically grows close to the ground, reaching a maximum height of around 6 inches.
  • Wide blades: The blades of crabgrass are broad and can be up to 1/4 inch wide, with a unique pale green or yellowish-green color.
  • Branching from a central stem: Crabgrass plants feature a central stem from which numerous branching leaf blades emerge.
  • Produce seeds prolifically: One of the biggest challenges with crabgrass is its ability to produce a large number of seeds, which can easily infest and spread throughout your lawn.

Growth Habits and Control Methods for Crabgrass

Understanding the growth habits of crabgrass is essential to effectively control its spread. Here are some key insights into its growth patterns and methods to control it:

  • Germination and growth: Crabgrass seeds generally germinate when soil temperatures reach around 55 to 60°F (12 to 15°C). Once established, it can quickly grow and establish a strong foothold in your lawn.
  • Prevention: To prevent crabgrass from taking over your lawn, a combination of cultural practices and herbicide applications can be employed. Regular mowing, maintaining proper lawn health, and ensuring adequate soil fertility can create conditions unfavorable for crabgrass growth.
  • Post-emergent herbicides: If crabgrass has already become a problem, post-emergent herbicides specifically formulated to target this weed can be utilized. These herbicides work by killing the actively growing plants while minimizing damage to desirable grass species.
  • Manual removal: For small infestations, hand-pulling or digging out crabgrass plants can be effective, especially when done before they produce seeds.

Characteristics of Johnson Grass

Johnson grass, also known as Sorghum halepense, is a perennial grass that belongs to the Poaceae family. It is a warm-season grass that thrives in full sunlight and can tolerate a wide range of soil conditions. Some distinctive characteristics of Johnson grass include:

  • Tall stature: Johnson grass can grow up to 8 feet in height, towering over many other plants in your garden or lawn.
  • Narrow leaves: The leaves of Johnson grass are long and slender, typically measuring around 1 inch in width.
  • Rhizomatous growth: Unlike crabgrass, Johnson grass spreads through an extensive network of underground stems called rhizomes. This allows it to form dense clumps and quickly colonize large areas.
  • Flowering and seeding: Johnson grass produces attractive purplish or reddish flowers and abundant seeds, which contributes to its ability to invade and spread rapidly.

Growth Habits and Control Methods for Johnson Grass

Understanding the growth habits of Johnson grass is crucial for its management. Here are some insights into its growth patterns and control methods:

  • Perennial persistence: Johnson grass is a pernicious perennial weed that can be challenging to eliminate once established. Its ability to regrow from rhizomes even after mowing or herbicide treatment poses a significant challenge.
  • Prevention: Preventing Johnson grass from establishing itself in your lawn or garden is the most effective approach. Regularly monitoring your outdoor spaces and promptly removing any new growth or rhizomes can help prevent its spread.
  • Chemical control: Herbicides specifically designed to target perennial grasses, such as glyphosate, can be effective in controlling Johnson grass. However, caution must be exercised to avoid damaging nearby desirable plants.
  • Mechanical removal: Physically removing the rhizomes and plants through digging or tilling can be an option. However, it requires diligence, as any remaining rhizome fragments can regenerate into new plants.

Impacts on Lawns and Gardens

Both crabgrass and Johnson grass can have significant impacts on the health and appearance of lawns and gardens. However, their impacts differ in several ways:

  • Competition for resources: Crabgrass, due to its low-growing nature, can compete with desirable grass species for sunlight, water, and nutrients. It can result in thinning of the lawn and disrupt the overall uniformity.
  • Aggressive invasion: Johnson grass, with its tall stature and rhizomatous growth habit, can outcompete and displace desirable plants in gardens and other landscaped areas. Its ability to spread rapidly can quickly turn it into a dominant presence.
  • Allergenic potential: Some individuals may experience allergic reactions upon contact with crabgrass pollen, while Johnson grass has fewer reported cases of allergies. However, caution should be exercised as individuals may have different sensitivities.

In conclusion, understanding the similarities and differences between crabgrass and Johnson grass is crucial for effective management and control. While both are invasive grass species, they differ in their growth habits, characteristics, and impacts on lawns and gardens. Employing the appropriate control methods, such as regular maintenance, herbicide applications, and manual removal, can help mitigate their spread and protect the health and aesthetics of your outdoor spaces. By staying vigilant and taking necessary precautions, you can effectively combat these unwanted grass invaders and maintain a beautiful and thriving landscape.

Identifying Grassy Weeds: Johnsongrass

Frequently Asked Questions

What is the difference between crabgrass and Johnson grass?

Crabgrass and Johnson grass are both types of invasive weeds commonly found in lawns and gardens. While they may seem similar, there are several key differences between the two:

How can I identify crabgrass and Johnson grass?

Crabgrass is a low-growing annual weed with thin, light green leaves that radiate from a central point. It forms a dense mat-like growth pattern close to the ground. On the other hand, Johnson grass is a perennial weed with tall, coarse stems and wide, coarse leaves. It can grow up to 6 feet in height.

Which weed is more difficult to control, crabgrass or Johnson grass?

Both crabgrass and Johnson grass can be challenging to control, but Johnson grass is generally considered more difficult due to its perennial nature and deep-rooted system. Crabgrass is an annual weed, which means it completes its life cycle in one season and reproduces by producing seeds. Johnson grass, on the other hand, spreads through both seeds and an extensive underground root system known as rhizomes.

Can I use the same methods to control crabgrass and Johnson grass?

While some control methods may overlap, it is important to tailor your approach to each specific weed. Pre-emergent herbicides are commonly used to prevent both crabgrass and Johnson grass from germinating, but post-emergent herbicides may be necessary for Johnson grass as it can be more resistant. Physical removal, such as pulling or digging, can be effective for crabgrass, but it may not be as successful for Johnson grass due to its extensive root system.

Are crabgrass and Johnson grass harmful to my lawn and garden?

Both crabgrass and Johnson grass can be detrimental to the health and appearance of your lawn and garden. They compete with desired plants for nutrients, water, and sunlight, which can lead to poor growth and even death of your desired plants. Additionally, their rapid spreading nature can quickly overtake an area if left untreated.

Can I prevent crabgrass and Johnson grass from invading my lawn and garden?

While it may not be possible to completely eliminate the risk of crabgrass or Johnson grass invading your lawn and garden, there are steps you can take to minimize their presence. Maintaining a healthy, thick lawn through proper watering, mowing, and fertilization can help prevent weed growth. Additionally, applying pre-emergent herbicides before the weeds germinate can provide some control.

Final Thoughts

Crabgrass and Johnson grass are two prevalent types of weeds that can cause headaches for homeowners and gardeners alike. While both grasses are invasive and can quickly take over lawns and gardens, there are some key differences between the two. Crabgrass is an annual weed that spreads through its seeds, while Johnson grass is a perennial weed that spreads through its rhizomes. When it comes to controlling these weeds, prevention is key. Regular mowing, proper watering, and a healthy lawn can help to minimize their growth. In cases where crabgrass or Johnson grass have already taken hold, using herbicides can be an effective solution. However, it’s essential to choose the right herbicide for the specific weed, as some products may be more effective against crabgrass while others target Johnson grass. Ultimately, understanding the characteristics and methods of control for crabgrass vs Johnson grass is crucial in maintaining a weed-free lawn or garden.