When evaluating granular products for turf and landscape applications, particle size plays a critical role in performance and application accuracy. One common term used to describe particle size is SGN, or Size Guide Number. SGN applies to a wide range of granular products - not just fertilizers, but also insecticides, herbicides, pesticides, and other granular inputs.
What Is SGN?
SGN represents the average diameter of a granular particle (prill or granule) measured in hundredths of a millimeter using specialized laboratory equipment. This standardized and precise method allows applicators to accurately compare particle sizes across different products and manufacturers.
While SGN itself is an exact laboratory measurement, slight variations in raw materials and manufacturing conditions can cause minor differences in particle size distribution from batch to batch. To maintain consistency and provide practical guidance in the field, The Andersons communicates SGN within defined size ranges rather than relying solely on a single numerical value.
The Andersons SGN Classifications
The Andersons categorizes granular products using the following SGN classifications:
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Standard (SGN 200+)
Easy-to-spread large granules designed for taller-cut turf such as lawns and rough. -
Fairways (SGN 120–199)
Medium-sized granules ideal for finely cut, dense turf like fairways and sports fields, where more particles per square foot and effective penetration through the canopy are required. -
Greens (SGN 100–119)
Small granules suited for greens, collars, approaches, and tees, where precision and even coverage are critical and particle size does not affect ball roll. Recommended for application with a precision spreader like the SR2000 Pro. -
Microgreens (SGN 99 and below)
Very fine granules designed for ultra-low mowing heights, delivering the most particles per square inch with no disruption of play. Recommended for application with a precision spreader like the SR2000 Pro.
Selecting the Right SGN
When choosing a granular product, consider the target site, mowing height, application rate, and spreader calibration. SGN is about selecting the particle size that can move through the turf canopy to reach the soil effectively without interfering with playability or affecting ball roll on closely mown surfaces like greens.
