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How Much Fertilizer Should I Put On My Lawn?

Calculating how much fertilizer you should apply to your lawn requires a bit of legwork. There are multiple factors that will need to be taken into account, including the size of your yard and what type of grass is growing in it. In most areas of the country, fertilizer application should begin around the middle of April (or when the ground temperature has reached 55 degrees Fahrenheit), so if you haven’t gotten a start on it yet, now’s the time!

The Numbers Matter

When you look at a bag of fertilizer in a store, you’ll notice that the label has three different numbers on it. These numbers display the amount of nitrogen, phosphate, and potassium that is in the bag of fertilizer. Nitrogen is an element that plants require for growth, and potassium provides plants with additional nutrients for overall health and vigor.

A bag with the numbers 25-10-15 will be comprised of 25% nitrogen, 10% phosphate, and 15% potassium, respectively. The rest of the mixture will generally consist of fillers that help provide an even application.

Look For a Slow Release Formula

Fertilizers that slowly release and breakdown their nutrients over time are preferable because it means that you can wait longer between applications. Depending on your specific lawn, a slow release formula will allow you to go 6 to 9 weeks between applications. Conversely, a non-slow release fertilizer will need to be applied every four weeks.

How Much Fertilizer Does My Lawn Actually Need?

How much fertilizer your lawn requires will depend on the percentage of nitrogen in the bag of fertilizer you are considering buying.

Any bag of fertilizer will come with a recommended application rate. Most of these recommendations are based upon 1,000 square feet of lawn.

If you want to manually calculate the amount of fertilizer you’ll need for a single application, simply divide the square footage of your lawn by 1,000 and multiply that by the corresponding number on the chart.

On a side note, if you mow your lawn often enough, the grass clippings that are left on your lawn will also add nitrogen to the soil so you can reduce the amount of fertilizer that is applied by roughly 25%. (Although a common belief, leaving lawn clippings on your grass will not cause thatch to develop.)

Don’t Forget About the Water

The more often you water your lawn, the more fertilizer it is going to require. Water encourages growth, and so more fertilizer is needed. When your grass grows, it consumes more nutrients. If you have a sprinkler system installed on your lawn, plan on laying down fertilizer about every six weeks. If you do not have a sprinkler system, you can wait up to eight weeks between applications.

Make sure to read the label on the bag of fertilizer you are using because it will contain specific instructions for watering your lawn before or after laying down fertilizer. For example, if you are using a granular fertilizer, you will more than likely be required to water your lawn before applying it, since granules require moisture to break down.

Be Thoughtful

Finally, should fertilizer wind up on your sidewalks or driveway, take a few minutes to sweep it up instead of allowing the rain to wash it away. If you allow the rain to take care of it, there is a chance that the fertilizer could wind up in streams or rivers, and this just adds pollution to the environment. When you sweep up spilled fertilizer, you are being kind to the environment around you.

About the author

Mark Kelly

Hi, I'm Mark the owner of Yard Care Gurus. I love to be outside working on my lawn, planning my next project. I created this website to help people like you find the best products for yard care and great advice. Thanks for stopping by!

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