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Ask a Specialist: Can You Share Lawn Fertilizing Tips?

Thursday, Apr. 17, 2014

April 17, 2014

Contact: Taun Beddes, 801-851-8465,

Ask a Specialist: Can You Share Lawn Fertilizing Tips?

Answer by: Taun Beddes, Utah State University Extension horticulturist

            The weather is finally warming, and most homeowners will once again begin their quest to grow a healthy, green lawn. An important factor in having a healthy lawn is proper fertilization. Unfortunately, lawn fertilization can be confusing, due to the many choices available. It is not uncommon for some garden centers to carry up to 20 or more lawn fertilizer blends. Consider these tips to take the mystery out of fertilizing.

            • Test your soil. A basic fertilizer test, which costs $14, reveals many important factors, including soil pH, salinity, soil texture (clay, loam, etc.) and the levels of phosphorus (P) and potassium (K) in the soil. These factors determine which fertilizer blend to apply. To learn more about soil testing, visit Local Extension offices also have soil test collection kits available free of charge.

            • Read the bag. Fertilizers include a three-number formula on the bag that lists the percentage of nitrogen (N), phosphate (a P source) and potash (a K source). A fertilizer with an analysis of 25-10-5 contains 25 percent nitrogen, 10 percent phosphate and 5 percent potash. By weight, a 50-pound bag of this blend contains 12.5 pounds of nitrogen, 5 pounds of phosphate and 2.5 pounds of potash. Utah soils commonly contain sufficient P and K for turf needs. However, test your soil to be sure. If your soil contains sufficient P and K, you should use a fertilizer containing N only, which is less expensive. It additionally reduces potential ground water pollution.

            • Consider a slow-release nitrogen fertilizer. It still greens up the lawn but slows how rapidly the grass grows, as long as it is applied correctly. This reduces the frequency of mowing needed and reduces potential pollution. Frequency of application depends on how the lawn is used. Turf receiving little traffic requires only one or two fertilizations per year. Moderately used turf, including turf where children play often and turf occasionally used for garden parties requires two to three applications per season. Only the most heavily used turf requires four or five applications. Application instructions on fertilizer bags include information on how much to use.

            • Apply at the right time. During the spring, the first application should be made in May. If pre-emergent weed control is needed, apply it at the time when forsythia shrubs bloom.

            Pre-emergent weed control is often bundled with fertilizer and should be applied in April. The next most important time to apply is in late October or early November.


            Direct column topics to: Julene Reese, Utah State University Extension writer, 435-797-0810 or

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