Zoysia grass is a popular warm season lawn grass known for its ability to tolerate heat, drought, and some foot traffic. However, despite its resilience, zoysia is still susceptible to issues like overwatering. Overwatering zoysia grass can lead to a number of problems, including fungal diseases, root rot, and an unattractive yellowing of the blades. Knowing how to identify and correct overwatered zoysia can help homeowners get their lawn back to its lush, green glory. In this article, we will cover the signs of overwatered zoysia grass, examine the causes, and discuss remedies to restore health and vigor.
Signs of Overwatered Zoysia
There are a few key visual indicators that can help determine if zoysia grass is being overwatered. These include:
Yellowing Blades
One of the most common signs of overwatering in zoysia is a overall yellowing of the leaf blades. This happens because excessive moisture prevents the roots from taking up vital nutrients like nitrogen from the soil. Without enough nitrogen, the blades lose their healthy green color and turn yellow. This yellowing can occur in patches or affect the entire lawn.
Thatch Buildup
Thatch is a tightly packed layer of dead and living grass stems and roots that develops between the soil and green vegetation. While a thin layer of thatch is normal, excess moisture encourages the rapid buildup of thatch. As thatch accumulates, it prevents water, oxygen, and nutrients from reaching the soil and roots. Zoysia with a thick layer of thatch tends to have yellowed, thin turf.
Mushrooms
The frequent moisture of overwatering encourages mushroom growth in lawns. Large mushroom patches popping up in a zoysia lawn, especially during damp conditions, can indicate a problem with too much irrigation. While not inherently dangerous, mushrooms signal conditions that may foster lawn fungus and other issues.
Moldy Smell
Excess waterlogged in the soil can create an anaerobic environment lacking in oxygen. This environment allows mold and other unfavorable organisms to thrive, producing a strong musty odor from the lawn. If zoysia grass gives off an unpleasant rotten smell, overwatering may be to blame.
Root Decline
One of the most serious effects of overwatering zoysia is weakened, decaying roots. With too much ground moisture, roots essentially suffocate and rot. Damaged roots turn brown, slough off, and die back. This makes the grass highly vulnerable to stresses and disease.
Fungal Diseases
The persistent moisture, high humidity, and poor soil conditions caused by overwatering are ideal for fungal zoysia diseases like dollar spot, brown patch, and zoysia patch. These diseases manifest as circular patches of matted, thin, discolored turf across the lawn.
Causes of Overwatered Zoysia
Zoysia grass only requires about 1-1.5 inches of water per week from irrigation during the growing season. Overwatering occurs when zoysia receives excessive amounts beyond this need. Some potential causes include:
Improper Irrigation Scheduling
Applying too much water too frequently is a common cause of overwatered zoysia lawns. Irrigating every day or multiple times a week will lead to soil saturation. Proper irrigation scheduling is vital. Zoysia generally only needs watering 2-3 times weekly during hot, dry periods.
Heavy Rainfall
Excessive rain, such as during a tropical storm, can cause temporary overwatering of zoysia. Drainage issues that prevent standing water from properly percolating through the soil can exacerbate the problem.
Compacted Soil
Dense, compacted clay soils do not allow water to percolate properly. Water can pool on the surface or take a long time to drain from the soil. Soil compaction worsens natural drainage and makes overwatering more likely.
Improper Sprinkler Use
Mistakes in sprinkler placement, setup, and maintenance can lead to uneven, excessive watering in parts of the lawn. Overspray hitting concrete surfaces that then flows into the grass can also oversaturate sections.
Shallow Roots
Zoysia grass with a shallow root system is more prone to becoming waterlogged. Roots weakened by disease, improper mowing, or poor soil conditions cannot grow deeply and can drown with too much moisture.
New Sod or Seed
Newly laid sod or seeded zoysia requires more frequent irrigation until the grass establishes. It’s easy for inexperienced homeowners to overdo watering at this stage, causing problems.
Corrective Measures for Overwatered Zoysia
Restoring an overwatered zoysia lawn back to health requires adjusting watering practices and addressing any underlying issues. Recommended corrective measures include:
Improve Drainage
Fixing any drainage problems is imperative to allow proper water flow through the soil. Installation of drainage tiles, grading improvements, or organic topdressing can all help. Aerating compacted soil also aids drainage.
Adjust Watering Schedule
Cut back on irrigation frequency and amounts. Water only when the top 1-2 inches become dry. Adhere to a 2-3x weekly schedule, and avoid excessive application rates. Letting the soil partially dry out between waterings is key.
Let Grass Dry Out
Allow zoysia to dry out for a period of about two weeks, only providing water if severe wilting occurs. This encourages the grass to grow deeper roots to access moisture.
Reduce Thatch Buildup
Thatch accumulation exacerbates overwatering issues. Dethatching mechanically or via aerification helps lessen this layer to improve drainage and root growth.
Treat Disease Issues
Fungal diseases weakening the lawn may require antifungal treatments alongside reduced watering. Treat accordingly and promptly remove diseased patches.
Apply Fertilizer
Applying a balanced nitrogen fertilizer provides a nutritional boost to zoysia suffering from root damage and nutrient deficiencies. This aids recovery.
Re-sod Damaged Areas
Sections of zoysia experiencing severe dieback may need replacement. Once moisture issues are corrected, re-sodding completely dead spots kick-starts regrowth.
Preventing Overwatered Zoysia
Adjustment of lawn care practices can help avoid overwatering issues in the future:
Water Early Morning
Water zoysia in the early morning between 4-10am. Avoiding heat peak periods lessens evaporation and waste.
Use Smart Irrigation Controller
Smart controllers adjust the watering schedule based on weather, eliminating guesswork and overwatering risk.
Check Soil Moisture
Use a moisture meter probe or screwdriver test routinely to assess soil moisture levels before watering. Only water if soil is dry at a 2-3 inch depth.
Improve Soil Quality
Amend soil with compost annually to improve drainage and rooting depth, reducing vulnerability to overwatering.
Locate Sources of Runoff
Detect areas where sprinklers or rainwater excessively pools, signaling a need for grading adjustments to direct runoff properly.
Conclusion
Overwatering can happen easily to even drought-resistant grasses like zoysia. Paying close attention to moisture levels and adopting wise watering habits is key. Indicators of overwatering like fungal disease, yellowed turf, and shallow roots require quick diagnosis and correction. With proper cultural practices that avoid excessive irrigation, zoysia can thrive in a healthy, vigorous state despite occasional rainfall extremes. Correcting overwatering issues promptly reduces lawn decline and protects the time and investment homeowners put into maintaining a lush zoysia lawn.
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Keywords
zoysia grass, overwatering, irrigation, drainage, yellowing, lawn fungus, turfgrass diseases, mushroom growth, moldy smell, root decline, thatch, aerification, lawn repair