Does Keeping Grass Longer Make It More Drought Resistant?

There's a common debate among homeowners regarding the height of lawn grass and its resilience during drought conditions. This article explores whether keeping grass longer can indeed make it more drought resistant. We will examine the scientific basis for this claim, practical considerations, and expert advice to provide a comprehensive understanding.

Understanding Drought Resistance in Grass

Drought resistance in plants refers to their ability to withstand periods of water scarcity without suffering significant harm. This can involve physical and physiological adaptations, such as the ability to reduce water loss or improve water uptake.

Empirical Evidence: Observational Data

Observational data strongly suggests that longer grass is more moisture-resistant and requires less frequent watering. For instance, a neighbor with a mowed lawn at an inch high (1 inch) notices that their grass is always more dry compared to the neighbor who keeps their grass at 3.75 inches. Longer grass tends to stay moister for longer, making it more equipped to withstand dry spells.

The Science Behind Grass Height and Watering Needs

First, longer grass provides a greater surface area for photosynthesis. Photosynthesis is a crucial process that helps the grass produce the energy it needs for growth and maintenance. A larger surface area means more leaves are available to capture sunlight, thereby enhancing the plant's ability to produce food and retain moisture.

Second, longer grass typically has deeper roots. Deeper roots allow the grass to access water reserves further below the soil surface, which can be crucial during periods of drought. In contrast, shorter grass tends to have more shallow root systems, making it more vulnerable to water scarcity at the surface level.

Lastly, taller grass has a more extensive thatch layer, which can act as a mulch, reducing evaporation from the soil surface and maintaining soil moisture.

Practical Considerations

While longer grass can enhance drought resistance, it is essential to strike a balance. Overly long grass can make the lawn vulnerable to other issues, such as fungal infections, pests, and aesthetic problems.

It's also important to consider the local climate. In extremely arid regions, even moderately long grass may face difficulties. In such cases, irrigation strategies and plant selection might be more effective.

Expert Advice and Recommendations

Experts recommend maintaining a grass height between 3 to 4 inches. This range provides the right balance of moisture retention, nutrient uptake, and resilience to stress. The exact height can vary based on the type of grass and local environmental conditions.

Watering practices should be adjusted based on local climate, grass type, and rainfall patterns. Deep, infrequent watering is generally more effective than frequent light watering, as it encourages deeper root growth.

Conclusion

Keeping grass longer can indeed make it more drought resistant, thanks to better photosynthesis, deeper roots, and a more extensive thatch layer. However, this approach must be balanced with other considerations such as local climate, grass type, and maintenance needs. By understanding the underlying principles, homeowners can create a more resilient lawn that can better withstand dry conditions.

References

1. Iowa State University Extension and Outreach - DHG1302, "Does Grass Height Affect Water Usage?"

2. University of Wisconsin Extension - L-1966, "How much water do grass types need?"

3. University of Minnesota Extension - LAWN 9, "How to maintain drought-tolerant lawn."