Phosphorus Fertilizer in Your Lawn or Garden

By: Julie Day

Most fertilizers no longer contain phosphorus.

Why are many fertilizer bags labeled ‘phosphorus free’? I thought phosphorus was one of the three important nutrients for plants?” -Madison

You’re right that phosphorus is an important nutrient, but fertilizers containing phosphorus are a major source of groundwater contamination. Did you know that phosphate fertilizers:

  • Run off into streams and lakes to create algae blooms that are toxic to humans and kill fish.
  • End up in the ocean, where they contribute to oceanic “dead zones.”
  • The methods to process rock phosphate cause the release of radioactive waste!

Many states now have regulations limiting fertilizers, detergents, and other products made with phosphates in an attempt to control pollution. That’s why the phosphorus number (the middle number) on your fertilizer bag is usually zero. The exception to this is so-called “starter” fertilizer, which contains higher phosphorus levels specifically to help new seeds to sprout.

If you test the soil in your lawn or garden, you’ll probably find you don’t need to add phosphorus, since most soil contains enough naturally.

I use bone meal and/or compost when planting new shrubs.

There are only two times when I want extra phosphorus for my garden:

  • When planting shrubs and trees, especially if I’m transplanting something with lots of broken roots. Phosphorus helps with root growth and establishment of new plants.
  • Mixed into the vegetable garden. Phosphorus helps with the production of fruits and vegetables, particularly root crops.

Here are some lawn and garden tips for protecting the environment:

  • Use compost! Composted fruits and vegetables provide plenty of natural phosphorus for your garden in a slow-release, organic form.
  • Adding organic matter helps the soil release natural phosphorus to your plants, making it (and other nutrients) more absorbable.
  • When you need additional phosphorus, use an organic source such as bone meal, soy meal, manure, or bat guano. While rock phosphate is considered an organic source of phosphorus, the radioactive byproducts formed during production can be detrimental to the environment.
  • Avoid fertilizers, dish detergents, and laundry detergents that contain phosphate. Manufacturers are catching on, and many products are now clearly labeled phosphate-free.
  • Educate your community about the need for reducing fertilizer runoff.

Always choose phosphate-free products.

Further Information




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5 Comments on “Phosphorus Fertilizer in Your Lawn or Garden”

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  • Official Comment:

    Thomas Boni Says:
    October 15th, 2018 at 6:09 pm

  • Jeff Says:
    October 15th, 2018 at 12:08 pm

    So Scotts removed the phosphorus from their fertilizers. My soil test from Penn State shows my phosphorus levels are low. How about promoting proper fertilizing procedures instead.

  • Kristen Says:
    October 7th, 2017 at 12:47 pm

    I recently had my soil tested thru the University of Tennessee Institute of Agriculture. My phosphorous tested at 650 and my Potassium tested at 280– both are excessively high.
    We are getting ready to aerate and over seed our lawn and the lawn care company insists on using a starter fertilizer. I am hesitant to add more of these to my soil. Unfortunately, I don’t see results for Nitrogen testing. Those were left blank. Would you recommend a starter fertilizer or not?
    We will be using Tall Fescue

  • john borgerding Says:
    September 21st, 2012 at 3:27 pm

    In response to jonathon hale’s comments (4-4-2011) – I AGREE 100% !! This is all just political hocus-pocus! I just use STARTER FERTILIZER on my lawn twice a year and they don’t get over on me.

  • jonathan hale Says:
    April 4th, 2011 at 4:08 am

    According to numerous university studies, your statement that fertilizers are a significant source of phosphorus pollution is incorrect. That fallacy has been resurrected repeatedly for years and been disproven. The legislation removing phosphorus from fertilizers is a political effect, not a scientific. Passing such laws distracts from effective and authentic fact-based solutions as the subject gets dropped and the agitated voter goes away.

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Phosphorus Fertilizer in Your Lawn or Garden