Milorganite vs Ironite: Which Is Best For Your Lawn?

We all treat our lawns and pets like our kids so we want them to grow and look healthy. Don’t we?

And it is healthy when it is glowing in rich green color.

Sometimes you are fulfilling all the basic requirements still the lawn doesn’t seem happy. This is the sign that your lawn needs fertilizer as your plants do not just require water and sunlight but nutrients as well to grow and flourish well.

Milorganite and ironite are two reliable fertilizers we all have heard of. We all know what they are for and how they are used but newbies get confused as they both are 100% effective in doing their jobs.

Milorganite and ironite are two different lawn care fertilizers that are made to serve different purposes.

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This brief guide is going to answer all the raising questions in your mind. But let’s get to know milorganite and ironite first.

What Is Milorganite?

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Milorganite is among the few branded fertilizers that are composed of heat-dried microbes. It is a product of the Milwaukee Metropolitan Sewerage District. The oldest chemical-organic blend that has been around for so many years is known for improving soil quality.  Being 85% organic and 15% synthetic, it is safe and easy to use with fewer chances of burning down the lawn. 

How is Milorganite made?

The company gathers the wastewater from the district and microbes are left in that water when they are done collecting the nutrients that water is sent back to the lake and the microbes are dried and then packed to bring a smile on gardeners’ faces. 

How does Milorganite work?

It’s a slow-release fertilizer so there would be no immediate results. It releases its content when microbial activity takes place. Microbial activity occurs when soil adequately moistens and its temperature is somewhere between 55 to 85F. When the soil reaches this point the fertilizer starts delivering the nutrients to the deserving parts.  It works only when the ideal soil condition is achieved otherwise the nutrients won’t move.

Once applied nutrients will be available for 10 weeks.

What does it do?

It promotes better growth, a healthy root system, and a dark green color.

How many bags of milorganite is enough for you?

You will be needing:

1 bag- 2500 square feet.

5 bags- ¼ acres 

6 bags- ⅓ acres

9 bags- ½ acres

12 bags- ⅔ acres

13 bags- ¾ acres

18 bags- 1 acre

Milorganite has a strong bad odor

Milorganite is an organic fertilizer so it does have a noticeable bad odor. But goes away as soon as it is applied to the soil. 

Milorganite does not stain

Synthetic fertilizers are disliked for their staining the concrete and pathways part. Since it does not contain salts like ironite, so it does not stain the roadways.

Application of Milorganite

For each below-mentioned case, it needs to be applied at least four times a year to see visible results. But if you are going to ignore the “four applications” advice as your lawn is healthy it is then recommended to fertilize the lawn in the fall season.

Case 01

Warm-Season Grass

First application: Around easter (when the turf breaks dormancy)

Second application: End of May.

Third application: Early September

Fourth application: Early October

Application Rate: 32 lbs per 2500 square feet.

Warm-season grass examples: Bermuda st. Augustine, Centipedegrass, Bahia, Zoysia.

Case 02

Cool-Season Grass

First application: End of May

Second application: Early July

Third application: Early September 

Fourth application: Mid November

Application Rate: 32lbs per 2500 square feet.

Cool-season grass examples: Kentucky Bluegrass, Fescue, Perennial Ryegrass 

Case 03

New lawns

First application: At the time of seeding.

Second application: At the time of sodding.

Application Rate: 64lbs per 2500 square feet.

What Is Ironite?

Ironite is a popular iron supplement that is used to bring life into burnt plants. As its name suggests ironite is an iron-rich product that shows its effects by bringing the rich green color out. Manganese, nitrogen, and potassium have been added to give plants a healthy boost. Ironite fertilizer comes in two forms.

  • Liquid ironite
  • Granular ironite

Both of them are equally beneficial. They are just made to suit your requirements. It works by balancing the PH level which in turn produces noticeable blooms.

Liquid ironite

Liquid ironite is made for alkaline and sandy soils. The liquid version is ideal for this type of soil as it is easier to absorb liquid fertilizer than the granular one.

Granular ironite:

Like most granular fertilizers, this product starts working as soon as it is spread and watered. It is suitable for both normal to clayey soils.


Can be used on grasses, flowers, trees, shrubs, and vegetables, etc.


At least once a year. Twice or thrice a year will bring fruitful results.

Application Rate: 1 pound per one hundred square feet.

Ironite, not a fertilizer

You may think you are reading a comparison between an organic and inorganic fertilizer but in fact, ironite is not a fertilizer but rather an iron supplement made to fulfill the iron deficiency of both large and small-scale lawns.

Why ironite label was changed, is safe for crops- the truth about this action

The Ironite label was changed a few years back and the company discontinued the original product because the mine that used to supply tailing, an active ingredient, was closed. The “now owners”( Central Garden& pet co.) have changed the product and called ” safe for food crops” in the label.

What you need to know about the “Say no to ironite” slogan?

Several public health and environmental advocates suggest you say “no to ironite” as it contains lead and arsenic. Lead and arsenic are not only harmful to kids but to adults and environments too. So they claim, using such fertilizers in places that are usually crowded with kids, pets, and adults is the biggest and deadliest threat to health. However, the truth about this allegation is yet not discovered but it’s a synthetic product it’s good for the said purpose but needs some interrogation for the concerns.

Milorganite vs Ironite Comparison

ManufacturerMilwaukee Metropolitan Sewerage DistrictPennington Seed Incorporated
Fertilizer or nutritional supplementFertilizerNutritional supplement
Harsh or notMild. Does not contain harsh chemicalsNot that mild. Contains harsh chemicals
Ratio5% nitrogen, 2% phosphorus, 32% potassium12% iron, 1% nitrogen, 1% potassium and some phosphorus
Organic or inorganic85% organic, 15% synthetic Inorganic
ApplicationFour times a yearAt least four times a year.
Safety measuresIt’s safe, no safety measure is needed.As it is 100% synthetic, it is recommended to wear full sleeves, long pants, and gloves while spreading the fertilizer in the soil.
How fast it worksTakes 7 to 8 days to show results.Takes two or three weeks to show results.
DrawbacksNo oneIt strains the concrete. Not an ideal choice for lawns with concrete walk paths.
OverdoseOverdose doesn’t burn.Overdose burns.
What’s bestIf your lawn is not iron having deficiencies, you want to improve your soil condition. If your lawn is having iron deficiency and leaves are turning yellow.
AvailabilityA little hard to find.Easily available.
Does it need a soil test?It can be applied with or without a soil test.Can not be applied without a soil test.
AlternativesRinger lawn restores Greenup nutrient blend, Lawn star 16-4-8 liquid fertilizer, Innova 7-1-2 organic fertilizer by Andersons, Purely organic lawn food, Green edge slow-release fertilizer 6-2-0, and Simple lawn solutions.Dr. Iron, Ferrous sulfate, Iron Chelates, Fe-EDTA, Fe-EDDHA, and Rich lawn iron-rich All-purpose fertilizer.
AdvantagesStrengthens root, improves soil, promotes rich green color.Balances PH levels, promotes health, fulfills nutrient deficiency.
Slow or fastSlow-releaseFast
End ResultsGreener healthier lawnsGreener healthier lawns
Milorganite vs Ironite comparison

Milorganite or ironite- what’s more eco-friendly

We all know humans are polluting the environment while beautifying their backyards their houses and such other stuff.  Fertilizers are also polluting the environment as some of them contain ingredients that are harmful to this planet. We may not kick such things out of our planet but we can limit their use as it is our duty to keep the environment humans, animals, and several other species breathing in, safe.

For this important reason, you should always choose an eco-friendly fertilizer over the other harmful options.

Milorganite is environmentally safe as it is produced by recycling waste products. So, it is more eco-friendly than the popular iron supplement we are comparing milorganite here, ironite.

End of discussion -Consult a lawn care professional

Lawn health is important, even if you know everything about a product you still may not be aware of what your soil needs. 

Fertilizers work only when they are needed, and if this fertilizer is needed or not? Can only be judged by a lawn care professional.

To not end up disappointed, discuss your lawn problems with experienced professionals, and get your soil tested. And then decide what should be your go-to choice.

Frequently asked questions

Milorganite or ironite? Which one is better?

Both do an awesome job in their ways. They are made for different purposes ironite for greener leaves and iron deficiency and milorganite for better soil quality. 

Is ironite a fertilizer?

No, it’s not. It is rather a nutritional supplement. It contains nitrogen, potash, and minerals.

Does milorganite contain human feces?

It’s just a rumor somebody has spread to throw this worth using fertilizer in a trash can. It’s organic but it does not contain human feces it is just a composition of heat-dried microorganisms.

Is using too much ironite dangerous?

Yes, it is dangerous if it’s applied in the prescribed manner as iron overdose burns the leaves and grass.

Does milorganite fertilizer kill weeds?

No, fertilizers killing weeds are just cliche newbies believe in. So, it does not kill weeds but it prevents its growth by encouraging healthier plant growth. 

How do ironite turn the yellow leaves green again? 

Leaves turn yellow when they do not find enough chlorophyll for the food making process. Ironite, by fulfilling this demand, puts life into the lifeless yellow leaves.

Is using too much milorganite on plants dangerous?

No, not as dangerous as ironite, as it is organic and slow-release as well. So, it does not release its nutrients all at once. This, about the fertilizer, makes it less risky.

Should you expect burns while using milorganite?

Milorganite does not burn even in the driest and hottest weather. And the reasons for the evergreen color are:

– It does not contain salts.
– It’s an organic fertilizer.

Does ironite contain lead and arsenic?

It is said that ironite contains lead and arsenic but the manufacturer has never said a word about it and neither has added it to the list of ingredients. If these two ingredients have become the reason for the “say no to ironite” slogan it may not be 100% true but there could be some covered truth.

Golf courses use milorganite. How true is that?

It’s from 80 to 90% true. Milorganite is the reason for the most greener golf courses in America. We do a morganite for golf courses.

What is the ideal temperature for milorganite to be applied?

Fifty-five to eighty-five degrees Fahrenheit is the ideal temperature for milorganite to be applied.

How often can you apply ironite to your lawns?

Once is enough if the lawn is in a good state. Bus if it is badly damaged two or three times a year. 

Is it okay to apply milorganite in summer?

Yes, it totally okay. It does not contain any salt so it doesn’t dry out the leaves and grasses even in the hottest months and driest conditions.

Is milorganite good for Bermuda grass?

Yes, not just for Bermuda it is an excellent fertilizer for all types of grasses. Though the company has not mentioned Bermuda grass separately, they say it works for all types of grasses.

Is ironite toxic for pets and kids?

Yes, kids and pets should never be allowed to play around during the fertilizing process as certain harmful ingredients may abandon their ability to learn.

How long, after an ironite treatment, should kids not be allowed to play around the plants?

Kids and pets should be kept away for at least 48 hours.

Does milorganite have a bad odor?

Yes, like all organic fertilizer milorganite does have a bad odor and it’s because of its origins But as soon as it is added to the soil odor is not noticeable at all.


Milorganite and ironite are two ting products made to serve different purposes. These products are good for their jobs if they are applied in a prescribed manner. Miloraginte is 85% organic and 15% synthetic however ironite is all synthetic and fast working. Milorganite is a slow-release fertilizer that starts showing its results in a few weeks. Ironite got several complaints that it contains lead and arsenic so if you find it offensive for the environment there are some really good alternatives as well. In brief, comparing these two products is useless as they are made to serve different purposes. Summing up in a sentence, they are good for what they are made.

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