Ironite vs Milorganite: Differences, Uses and Reviews

Both Ironite and Milorganite are great sources of nutrients that boost the growth and color of grass in lawns. If your lawn is not growing thick and turning into a deep green color, it is time to use Ironite or Milorganite. But what is the difference between these two?

Ironite is a lawn supplement containing 20% iron and 1-0-1 NPK while Milorganite is an organic fertilizer containing 2.5% iron and 6-4-0 NPK. While Milorganite is a slow-release fertilizer that helps lawns grow faster and thicker, Ironite is a quick-release mineral for making grass greener.

A deep green color is a sign of a healthy lawn. While there are various ways to achieve it, water, sunshine, and manure may not always be enough. You may opt for Milorganite or Ironite to achieve a greener-looking lawn but Milorganite is better for your lawns. I have outlined the differences between Ironite and Milorganite, as well as my reviews of the two lawn products.

Ironite vs Milorganite: Differences + Comparison

Ironite vs milorganite differences for lawns

Both Ironite and Milorganite are natural fertilizers only that they differ in terms of composition and how they act – or what they do to lawns. When the grass starts to discolor and turn yellow, Ironite supplement helps it turn green and healthy again.

Milorganite is a slow-release nitrogen fertilizer that can feed your lawn for up to 10 weeks, helping the grass grow and green up faster. Milorganite is organic and does not burn the lawn even when overfertilized.

Here’s a table showing the differences between Ironite vs Milorganite:

Ironite Milorganite
Ironite is a nutrient supplement that is used as an additive.Milorganite is a fertilizer.
Contains 20% iron with other micro-nutrients.Has 2.5% iron content.
Is a 1-0-1 additive (lawn supplement).It is a 6-4-0 organic slow-release nitrogen fertilizer.
It is used as a supplement enriched with irons when grass begins to turn yellow.Milorganite is used as an organic fertilizer to strengthen the roots of your grass lawn and green ups the grass at a steady pace.
You’ll notice the results within a few days.It takes a few weeks to see the results.
Ironite provides the lawn with soluble iron and other nutrients for deep greening – fast.Milorganite feeds the lawn with soluble nitrogen with a little bit of iron for growth and greening.
Can burn the lawn if applied excessively, during hot weather (above 80 degrees), or when not watered in after application.Milorganite does not burn grass even when applied in excess or under hot temperatures because it has no salts.

One major difference between Ironite and Milorganite is that Ironite helps the lawn turn green without excessive growth while Milorganite helps grass grow thicker and fuller quickly while turning it into a deep green color at the same time. This difference owes to the NPK and iron ratios in the composition of the two.

When to use Ironite

Ironite will help your lawn turn green fast.
Ironite will help your lawn turn green fast.

Your grass will be susceptible to various changes during spring. The temperature rises and the days become longer, thus promoting rapid growth.

However, the spring’s cold soil suppresses the chemical and biological activities that make nutrients in the soil. This reduces the amount of iron available in the soil for the growth of your grass during spring. This is when you need to apply Ironite to fix the iron deficiency.

You should use Ironite when your lawn starts losing its green color and becomes yellow (chlorosis) due to Iron deficiency. Applying Ironite will help restore your lawn’s green color.

Pro tip: If your turfgrass is already thick, full, and growing faster yet not lush green, you can apply Ironite to help the grass green up a little with no extra growth.

The benefits of applying Ironite to your lawn include the following:

  • Turns turfgrass greener
  • Helps lawns use less water
  • Makes nutrients naturally available to grass
  • Contains calcium that helps with turfgrass disease resistance

Note that you’ll still need to feed your lawn with a good fertilizer even when using Ironite supplement. Liquid Ironite may also be an option where you need nitrogen fertilizer because it is a 7-0-1 NPK formulation with just 1% iron in it.

Application – Liquid Ironite vs Granular

The best way to apply Ironite to your lawn is to distribute it with a fertilizer between 4 to 10 times yearly depending on the condition of your lawn.

There are two types of iron available, liquid and granular.

  • You should use liquid Ironite with alkaline and sandy soil because these soils are notorious for allowing amendments to quickly wash past the roots after rainfall.

You can apply granular Ironite directly on the soil and water the water immediately to help the granules to adhere to the soil. Granular Ironite is best for loam lawns and clay soil.

When to use Milorganite

Ironite vs Milorganite - Making lawn thicker

Since Milorganite is a nitrogen fertilizer, you can use it as part of your yearly lawn maintenance program. In general, I’d recommend you apply it about 4 times per year because it is a slow-release fertilizer.

If you’re in the North-eastern United States, Midwest, or Pacific Northwest with cool-season grass like Fescue, Kentucky bluegrass, and Perennial Ryegrass, use Milorganite in the following times, here’s a good fertilizer schedule:

  • The end of May- apply 32 pounds per 2,500 square feet.
  • July 4th- apply 32 pounds per 2,500 square feet
  • Labor day- apply 32 pounds per 2,500 square feet
  • Mid November-apply 32 pounds per 2,500 square feet

For warm-season turfgrasses grown in the south, here’s a good Milorganite fertilizer schedule to follow:

  • Easter- apply 32 pounds per 2,500 square feet.
  • The end of May (Memorial Day) – apply 32 pounds per 2,500 square feet.
  • Labor day-apply 32 pounds per 2,500 square feet.
  • Early October-apply 32 pounds per 2,500 square feet.

Milorganite Application

  • Mix Milorganite into the top couple of inches of your top soil prior to applying your seed.
  • Apply two bags of 32 pound Milorganite for every 2,500 feet of grass after your seedlings have grown and you’ve mowed your lawn three times.
  • Continue this for the first one year.
  • After this, follow the application of one 32-pound bag for every 2,500 feet of grass.

Can I use Ironite and Milorganite together?

It is not a good idea to use Ironite and Milorganite together because too much iron is not only a waste of nutrients but also a risk of run-off into waterways and driveways where it will cause staining on concrete patios and driveways.

Milorganite manufactuers recommend against “using a variety of iron supplements on your lawn. Lawns can use only a limited amount of any nutrient, including iron.”

As such, it is not recommended to use Ironite together with Milorganite as these will not produce any better results in terms of greening and making the grass grow greener and thicker.

Which is better Ironite or Milorganite?

Milorganite is better than Ironite when you want to feed the grass and green up your lawn because it contains organic nutrients and iron as opposed to the concentrated chemical nutrients found in Ironite that can harm your lawn. Milorganite is a more natural product and is better especially if you have pets and kids.

Where you cannot find Milorganite, you might want to use a Milorganite alternative product that contains ferrous sulfate. It is, however, important to do a detailed soil test to determine if your grass is turning yellow due to iron and calcium deficiency before turning to products like Ironite.


Ironite is a 1-0-1 NPK supplement with 20% iron while Milorganite is a 6-4-0 organic fertilizer with 2.5% iron content. The difference is that Ironite helps lawns to green up without the grass growing excessively while Milorganite feeds and makes grass grow thicker, fuller, and greener.

The best fertilizer to use to restore your lawn’s beautiful dark green color is Milorganite. It is less harsh on your grass compared to Ironite which can burn your grass because of its harsh composition. However, you should use Ironite if the soil in your lawn is iron-deficient.

You can identify the iron deficiency if you notice the yellowing of your grass. Ironite also improves the health of your entire landscape by improving the health of your flowers and trees.


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