Lawn Care: Lawn Fertilizer

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What do those numbers on the package mean?

Fertilizer is comprised of three primary nutrients; Nitrogen, Phosphorous and Potassium. The symbols for these nutrients, respectively, are N - P - K. The numbers on fertilizer packages represent the ratio of the nutrient to the total weight of the package. So a 50 lb. bag labeled as 25-5-10 is 25% nitrogen, 5% phosphorous, 10% potassium. By multiplying the weight of the package, by the percentage of the nutrient, you can determine the number of pounds of each nutrient. So in the example above, .25 * 50 lbs = 12.5 lbs. of nitrogen, 2.5 lbs. phosphorous and 5 lbs. potassium.

So what is the rest of the bag contain? Mostly inert fillers. Why not make the bay lighter and leave those fillers out? Those fillers help with even distribution of the nutrients and in the slow-release of nutrients over time.

When should you fertilize?

The weather is the chief influence on when to apply nutrients. The beginning and end of the growing season are the two most important times to fertilize the lawn. These two applications will be adequate to sustain a healthy lawn. However, also preparing for the winter and fertilizing prior to the appearance of weeds will give you the best results.

Where you live influences the timing for each of these applications. If you live in a warmer climate, then the early and late summer are ideal for pre and post growth season applications. In colder climates, spring and fall are the best times to apply nutrients. Early summer is the time to apply nutrients to aid in the prevention of weeds.

For winter protection you should apply fertilizer prior to the first frost or in warmer climates, when the grass stops growing.

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