Fertilization Ratio of Kentucky Bluegrass


Kentucky bluegrass produces a lush, quickly spreading sod in cool, moist areas of the United States. While not drought or shade tolerant, it stands up to foot traffic and grows quickly. Kentucky bluegrass requires more maintenance than other types of grass, but produces a fine soft blade. Gardeners in dry areas may plant a blend of Kentucky bluegrass and more drought-tolerant varieties.


Fertilizers for Kentucky bluegrass come in several formulas. Most are granular synthetic fertilizers that contain primarily nitrogen and phosphorus. Slow-release formulas are more expensive, but break down gradually, releasing nutrients over several weeks or even months. Cornell University recommends slow-release fertilizers because they provide a long-lasting, easily used source of nitrogen for grass plants and they are less likely to burn roots. Slow-release formulas are also less likely to leach out of sandy soils, potentially polluting groundwater. Organic formulas such as corn gluten are just as effective as synthetics, according to Iowa State University.


Amounts may vary slightly depending on the formula. Iowa State University recommends 4 lbs. of fertilizer per 1,000 square feet of lawn, applied annually for most commercial preparations, including corn gluten. Researchers at the university applied 10 different fertilizer formulas to Kentucky bluegrass and noted the differences. Most of the brands showed similar results. The organic fertilizer, corn gluten, received high marks in all quality indicators.


Rotary spreaders apply fertilizer in a wide swath, but also throw fertilizer in unwanted places, such as the driveway and gutter. Without proper clean-up, fertilizers may stain hard surfaces and wash away with rain, polluting streams and ground water. Drop spreaders take a bit longer to use, but keep fertilizer on the lawn, reducing the chance of pollution. Apply only the recommended amount of fertilizer, advises Cornell University, clean up any spills and apply it correctly.

Time Frame

Fall is the ideal time to apply fertilizer, according to Cornell University, although high maintenance grasses such as a Kentucky bluegrass blend may benefit from a second application in mid-spring. Apply 2 lbs. of fertilizer per 1,000 square feet of grass around the end of May (Memorial Day) and the beginning of September (Labor Day). Divide the recommended amount into four yearly applications for pure Kentucky bluegrass lawns.


Many lawn fertilizer formulas contain pesticides and herbicides along with fertilizer. Avoid these products, known as "Weed and Feed," according to Thurston County, Washington Public Health and Social Services. Lawn pesticides and herbicides are known to cause cancer, reproductive problems and neurological diseases in humans and are especially dangerous to young children. They also pollute groundwater and streams and lakes, killing birds, fish and other aquatic life.

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About this Author

Julie Christensen has been writing for five years. Her work has appeared in "The Friend" and "Western New York Parent" magazines. Her guide for teachers, "Helping Young Children Cope with Grief" will be published this spring. Christensen studied early childhood education at Ricks College and recently returned to school to complete a degree in communications/English.