How to Out-Compete Poa Annua

Golf course

Understanding the Dynamics

  • Bentgrass: It’s crucial to note that while there are many bentgrass cultivars, creeping bentgrass (Agrostis stolonifera) is the most common type used on golf course putting greens. It truly excels in cooler conditions. Source: USGA.

  • Poa annua (annual bluegrass): While technically a cool-season grass, Poa annua’s heat tolerance varies significantly based on biotype. Some biotypes can be surprisingly aggressive in warmer climates. Source: University of Tennessee – Poa annua.

Key Strategies with Supporting Data

1. A Balanced Nutritional Approach:

  • Low Nitrogen: Studies have demonstrated that high nitrogen inputs increase Poa annua encroachment on bentgrass greens. Limiting nitrogen gives bentgrass a competitive advantage. Source: The Ohio State University – Nitrogen Fertilization Strategies.
  • Micronutrients: Research shows that micronutrients like iron and manganese are crucial for maintaining healthy bentgrass, fostering its ability to withstand stress and competition. [Source: Michigan State University – Micronutrients for Turfgrass]
  • Aquaritin & Similar Products: While research on this specific product is limited, the concept of utilizing soil microbes for gradual nutrient release aligns with sustainable turf management principles. Studies indicate that enhanced microbial activity can improve nutrient availability for turfgrasses. [Source: Penn State University – Microbial Activity for Sustainable Turf] 


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2. Optimizing Cultural Practices:

  • Irrigation: Research consistently supports deep, infrequent irrigation for strong bentgrass root development. [Source: PACE Turf – Bentgrass Best Management Practices] 

  • Mowing, Grooming, Verticutting: A wealth of data highlights how these practices impact the bentgrass/Poa annua balance depending on timing and intensity. Source: USGA Course Care – Managing Putting Greens with Mixed Populations

3. Selective Control and Suppression:

  • PGRs and Herbicides: The efficacy of these tools is backed by extensive research. [Source: Cornell University – Controlling Poa annua]


Promoting bentgrass dominance over Poa annua signifies a shift toward more sustainable golf course management. Lower fertilizer inputs, reliance on natural soil processes, and careful cultivation practices all reduce the environmental footprint of the course. This approach not only fosters beautiful playing surfaces but also demonstrates a commitment to responsible stewardship of our green spaces.

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