Zoysia grass, known for its dense, carpet-like texture and heat tolerance, is a popular choice for lawns across warmer climates. However, a common concern among homeowners considering Zoysia is its potential to aggressively spread and outcompete existing grasses. The question is: will Zoysia choke out other grass varieties? The answer, in short, is yes, Zoysia grass can indeed choke out other grasses under the right conditions. This article delves into the reasons behind Zoysia’s aggressive nature, the factors that influence its competitiveness, and strategies to manage its growth and prevent it from completely taking over your lawn – if that’s not your goal.
Understanding Zoysia Grass Characteristics
Zoysia grass, belonging to the genus Zoysia, encompasses several species, including Zoysia japonica, Zoysia matrella, and Zoysia tenuifolia, each with slightly different characteristics. All Zoysia varieties share a common trait: they are warm-season grasses, meaning they thrive in warm temperatures and go dormant during colder months.
Dense Growth Habit: Zoysia is characterized by its extremely dense growth habit. It spreads through both rhizomes (underground stems) and stolons (above-ground stems), forming a thick mat of turf. This dense growth makes it excellent at weed control because it crowds out many unwanted plants. However, it also contributes to its aggressive nature when competing with other grasses.
Slow Initial Establishment: While Zoysia is aggressive once established, it’s important to note that it is a slow-growing grass initially. This means that during the establishment phase, other grasses or weeds can easily compete with it. This slow establishment period is critical to understand when thinking about how to manage its spread in conjunction with existing grasses.
Heat and Drought Tolerance: Zoysia excels in hot and dry conditions. This gives it a significant advantage over cooler-season grasses, like fescue or rye, particularly during the summer months. Its ability to withstand these conditions allows it to continue growing and spreading while other grasses struggle.
The Competitive Edge: How Zoysia Chokes Out Other Grass
Zoysia’s capacity to dominate a lawn stems from a combination of its growth habit, environmental adaptability, and resource utilization. Its dense structure and spreading mechanisms allow it to effectively monopolize sunlight, water, and nutrients, depriving other grass species of what they need to survive.
Resource Depletion: Zoysia’s dense growth creates a barrier that prevents sunlight from reaching the lower leaves of other grasses. This shading effect inhibits photosynthesis, weakening the other grasses and making them more susceptible to disease and stress. Furthermore, Zoysia’s extensive root system competes aggressively for water and nutrients in the soil, further depriving other plants of essential resources.
Physical Encroachment: The rhizomes and stolons of Zoysia actively spread horizontally, physically encroaching on the territory of other grasses. As Zoysia spreads, it effectively smothers other plants, preventing them from growing and reproducing. This is particularly effective against grasses that do not spread aggressively themselves.
Allelopathic Effects (Possible): While research is ongoing, some studies suggest that certain Zoysia varieties may exhibit allelopathic properties. Allelopathy refers to the production and release of biochemical compounds that inhibit the growth of other plants. If Zoysia does possess allelopathic capabilities, this would further enhance its ability to outcompete other grasses.
Factors Influencing Zoysia’s Aggressiveness
The extent to which Zoysia chokes out other grasses is influenced by several factors, including the specific Zoysia variety, the climate, soil conditions, and management practices.
Zoysia Variety: Different Zoysia species and cultivars exhibit varying degrees of aggressiveness. For example, Zoysia japonica tends to be more aggressive than Zoysia matrella. Similarly, within each species, some cultivars are bred for faster growth and spread, making them more likely to dominate other grasses. The density of the turf formed also influences its competitiveness.
Climate: Zoysia thrives in warm climates with hot summers and mild winters. In these regions, it has a significant advantage over cool-season grasses. However, in colder climates, Zoysia’s growth is limited, and it may be less likely to choke out other grasses. The length of the growing season directly impacts how much it can spread.
Soil Conditions: Zoysia prefers well-drained soils with a slightly acidic to neutral pH. Poor soil conditions, such as compacted soil or excessive alkalinity, can hinder its growth and reduce its competitiveness. Proper soil preparation before planting Zoysia is crucial for its success.
Management Practices: Mowing height, fertilization, and watering practices can all influence Zoysia’s competitiveness. Mowing Zoysia too short can damage the turf and make it more susceptible to disease. Over-fertilizing can promote excessive growth, increasing its aggressiveness. Proper watering is essential for maintaining healthy turf.
Managing Zoysia Grass Growth
Whether you want to encourage Zoysia to take over completely or simply want to maintain a mixed lawn, understanding how to manage its growth is crucial.
Encouraging Zoysia Dominance: If your goal is to have a pure Zoysia lawn, you can encourage its dominance by providing optimal growing conditions. This includes proper soil preparation, adequate fertilization, and appropriate watering. You can also overseed with Zoysia grass seed or plugs to accelerate the process. Selective herbicides can also be used to eliminate competing grasses.
Preventing Zoysia Takeover: If you want to maintain a mixed lawn with other grass species, you need to take steps to control Zoysia’s spread. This can be achieved through several methods:
- Physical Barriers: Install physical barriers, such as edging, around Zoysia patches to prevent them from spreading into other areas of the lawn. These barriers should be buried deep enough to prevent rhizomes and stolons from growing underneath.
- Selective Herbicides: Use selective herbicides that target Zoysia grass without harming other grass species. However, it’s important to use these herbicides carefully, as they can still damage desirable grasses if applied incorrectly.
- Cultural Practices: Adjust your mowing height, fertilization, and watering practices to favor the other grass species. For example, mowing at a higher height can help shade out Zoysia, while avoiding over-fertilization can limit its growth.
- Regular Monitoring: Regularly monitor your lawn for signs of Zoysia encroachment. Remove any Zoysia that has spread into unwanted areas by hand or with a shovel.
Zoysia: The Right Choice for Your Lawn?
Deciding whether or not to plant Zoysia grass depends on your specific needs and preferences. Its heat and drought tolerance make it an excellent choice for warm climates. Its dense growth habit provides excellent weed control. However, its aggressive nature and slow initial establishment require careful consideration.
Benefits of Zoysia:
- Excellent heat and drought tolerance
- Dense growth habit for weed control
- Low maintenance requirements once established
- Attractive, carpet-like appearance
- Good wear tolerance
Drawbacks of Zoysia:
- Aggressive growth habit can choke out other grasses
- Slow initial establishment
- Turns brown in cold weather
- Can develop thatch buildup if not properly maintained
- May require specialized equipment for mowing
Ultimately, the decision of whether to plant Zoysia grass is a personal one. Carefully weigh the benefits and drawbacks, consider your local climate and soil conditions, and assess your willingness to manage its growth. Understanding its characteristics and competitive nature is key to making an informed decision and achieving a lawn that meets your specific needs and aesthetic preferences.
What makes Zoysia grass so aggressive?
Zoysia grass spreads through both rhizomes (underground stems) and stolons (above-ground stems), forming a dense, tightly knit turf. This dual propagation system allows it to aggressively encroach upon neighboring plant life, including other grasses, weeds, and even flower beds. The dense nature of its growth habit also effectively chokes out competition by blocking sunlight and preventing other plants from establishing a foothold.
Beyond its growth method, Zoysia also exhibits a remarkable tolerance for various environmental conditions. It thrives in full sun but can also tolerate partial shade, and it’s fairly drought-resistant once established. This adaptability, combined with its dense growth, allows it to outcompete less resilient species and steadily take over lawn areas, making it a highly aggressive competitor in a mixed-grass lawn.
How quickly does Zoysia grass spread?
The spread rate of Zoysia grass varies depending on several factors, including the specific cultivar, climate, soil conditions, and maintenance practices. Generally, newer, improved cultivars tend to spread more rapidly than older varieties. Warmer climates and well-drained, fertile soil can also accelerate its growth and expansion.
Under optimal conditions, some Zoysia cultivars can spread several inches per month via rhizomes and stolons. This relatively fast growth rate means that a small patch of Zoysia can significantly expand its territory within a growing season, potentially overtaking a large portion of a lawn in a few years if left unchecked and if conditions are favorable.
Can Zoysia grass outcompete other common lawn grasses?
Yes, Zoysia grass is highly competitive and can often outcompete other common lawn grasses, such as fescue, bluegrass, and ryegrass. Its dense growth habit creates a thick barrier that prevents sunlight from reaching the soil surface, hindering the germination and growth of competing grasses and weeds. The aggressive spreading nature of Zoysia ensures it will continually expand its territory at the expense of other grasses.
Furthermore, Zoysia’s tolerance to heat and drought gives it an advantage in many climates where other cool-season grasses may struggle, particularly during the summer months. This resilience allows Zoysia to maintain its dominance even when other grass types are stressed, further solidifying its position as the dominant species in the lawn.
How can I prevent Zoysia grass from taking over my lawn?
Preventing Zoysia from overtaking a lawn requires a multi-pronged approach focused on maintaining a healthy, competitive lawn and strategically controlling Zoysia’s spread. Regular fertilization, proper watering, and consistent mowing at the recommended height for your desired grass type will help to keep existing desirable grasses strong and less susceptible to Zoysia encroachment. Regularly monitor your lawn for any signs of Zoysia invasion.
Physical barriers, such as edging around flower beds and other areas, can help to contain Zoysia’s spread. If Zoysia appears, spot treat with a non-selective herbicide specifically designed for grass control, being careful to avoid damaging desirable plants. Severe infestations might require more drastic measures, such as removing the affected areas and reseeding with a more appropriate grass type.
What are the benefits of Zoysia grass despite its aggressiveness?
Despite its aggressive nature, Zoysia grass offers several benefits that make it a desirable choice for many homeowners. It forms a dense, durable turf that is resistant to wear and tear, making it ideal for lawns with high foot traffic or pets. Zoysia also boasts excellent heat and drought tolerance, requiring less frequent watering compared to many cool-season grasses.
Furthermore, Zoysia is relatively low-maintenance once established. Its dense growth habit helps to suppress weeds, reducing the need for herbicides. It also exhibits good disease resistance, minimizing the risk of common lawn diseases. While its aggressive spread requires management, the overall advantages often outweigh the challenges for homeowners seeking a resilient and attractive lawn.
Is it possible to contain Zoysia grass in a specific area?
Yes, it is possible to contain Zoysia grass within a specific area, although it requires consistent effort and strategic management. Installing physical barriers, such as edging made of metal, plastic, or concrete, around the perimeter of the Zoysia patch can effectively prevent its rhizomes and stolons from spreading into neighboring areas. The barrier should extend several inches below the soil surface to prevent underground runners.
Regularly monitoring the edges of the Zoysia patch and promptly removing any stray runners or seedlings that attempt to escape is crucial. You can also use herbicides specifically designed for grass control to spot-treat any Zoysia that encroaches on unwanted areas. Consistent vigilance and proactive management are key to successfully containing Zoysia grass and preventing it from overtaking the entire lawn.
If I don’t want Zoysia, how can I get rid of it completely?
Completely eradicating Zoysia grass can be a challenging task due to its aggressive nature and extensive root system, but it is achievable with persistence. The most effective method involves using a non-selective herbicide, such as glyphosate, multiple times over several weeks. Be sure to carefully follow the product instructions and take precautions to protect desirable plants from overspray. Complete coverage is crucial for success.
After the Zoysia is completely dead, remove the dead turf and any remaining rhizomes or stolons from the soil. Then, prepare the soil for reseeding or sodding with your desired grass type. It’s essential to continue monitoring the area for any new Zoysia growth and promptly address it to prevent re-establishment. Consider using pre-emergent herbicides to further inhibit Zoysia seeds from germinating. Consistent monitoring and treatment will eventually eliminate the Zoysia.