Milorganite vs Ironite – Differences + Which to Use on your Lawn

If you want deep green grass, you must provide your lawn with some additional nutrients on top of your routine fertilizer and watering. You can easily achieve this through the application of Milorganite or Ironite. So what’s the difference between the two?

Milorganite is a slow-release organic fertilizer containing soluble nitrogen to boost growth, phosphorus for root development, and iron to keep the lawn green. On the other hand, Ironite is a mineral supplement containing iron that instantly turns a yellowing lawn into a deep green color.

Ironite vs Milorganite – Differences

Here is a summary of the differences between Ironite and Milorganite:

It takes a few days to green up a lawn.It takes a few weeks to notice results after applying on your lawn.
Ironite is a mineral supplement used as an additive to turn grass green.Milorganite is a slow-releasing nitrogen fertilizer applied to grass to grow fast, fuller, thicker, and green up faster.
It has 20% iron content together with other micronutrients.Contains only 2.5 % iron content.
Contain salts that can burn the lawn when applied excessively, especially when the weather is hot or when not watered in after application.Milorganite does not contain salts and cannot burn your lawn even when applied excessively.
Ironite contains 8% calcium.Milorganite contains 1.2% calcium.
Ironite is used to restore the green color when the grass turns yellowish.It is applied on the lawn to get a deep green color at a steady pace.
Ironite enriches the lawn with iron sulfate and other nutrients that enhance greening.Milorganite provides the lawn with soluble nitrogen and small quantities of iron to boost growth and greening.
Fertilizing lawns with Ironite helps to boost the green color without causing excessive growth.Milorganite also helps to make grass greener while promoting thicker growth.
Ironite is a 1-0-1 fast-release iron supplement for grass.Milorganite is a slow-release NPK fertilizer containing nutrients like nitrogen and phosphorus.


Ironite is a mineral supplement rich in iron. Plants require iron to create chlorophyll, a green pigment necessary for photosynthesis. Fertilizing your lawn with Ironite helps to make grass greener within a few days of application.

On the other hand, Milorganite is an organic fertilizer containing nitrogen, phosphorus, and small quantities of iron and calcium. Milorganite fertilizer has no scorching effects. It improves the health of your lawn as well as the quality of the soil.

Result timeframe

If you want a deep green lawn within a few days, Ironite will do the trick. The plants easily absorb liquid Ironite to give results within a few days of application. On the other hand, Milorganite takes more time before releasing nutrients into the soil, probably 3 to 4 weeks.

Soil fertility improvement

If you are looking for a product to promote greener growth and improve soil fertility, then Milorganite takes the lead. Milorganite is 85% organic and does not contain harmful metals like lead and arsenic that are present in Ironite.

Product Safety

Milorganite is safe to handle since it’s organic. On the other hand, Ironite is made from synthetic chemicals. Extra care should be taken when applying it to your plants. Ensure to wear gloves, gumboots, and a face mask when handling it.

Lawn greening

Milorganite and Ironite contain iron that helps turn yellowing lawns into greener colors. Milorganite contains other nutrients that help make your lawn greener and improve the soil’s quality. While Ironite is specifically for greening up plants.

Cost of the product

Cost is also considered when choosing the best product to use on your lawn. It’s a good idea to visit several shopping centers to compare the price tags. Generally, Milorganite is cheaper than Ironite.

Which is better to use on lawns?

If your grass turns yellow, it needs some iron to get green. Both Ironite and Milorganite contain iron. So, how do you know which one is better to use on the lawn? Let’s have a look at each one of them:


Ironite is not a complete fertilizer. Instead, it is a mineral supplement containing iron and other micronutrients. It can be applied on your lawn alone or together with other fertilizers. Its formula is 1-0-1, meaning it has little nitrogen and potassium with zero phosphorus.

Ironite contains quick-release iron, which helps to turn your lawn into a deep green color within a few days of application. It dissolves in water easily to be absorbed by the grass almost instantly.

This mineral supplement is applied on the lawn in addition to your regular fertilizer application. It is used to treat iron deficiency in the soil. It is recommended to apply Ironite on your lawn at least four times a year. However, do not exceed 10 applications per year.

Advantages of using Ironite on a Lawn

Fertilizing your lawn with Ironite promotes stronger and greener grass without excessive growth. When we compare Ironite and nitrogen fertilizers, both help make the grass greener. However, nitrogen fertilizers promote faster growth, giving you extra work to mow your lawn.

Ironite works fast to give positive results within a few days, unlike slow-release fertilizers, which may take a couple of weeks to show results.

Disadvantages of using Ironite on the lawn

Ironite has scorching effects. It may burn your lawn when applied excessively or in the wrong weather conditions. Hot weather conditions to be specific.

Many gardeners have also reported the issue of stains. Ironite is likely to stain anything it contacts, such as fences and concrete pathways.

There are also high chances of going overboard in the application of Ironite. Earlier, we saw that excess application can lead to lawn burnout. If you are using liquid Ironite, it is recommended to mix it with a natural dye to demarcate the areas treated.


Milorganite is a slow-release organic fertilizer containing soluble nitrogen to boost growth, phosphorus for root development, and iron to keep the lawn green. It also contains other micronutrients that are important to your lawn.

This fertilizer is ideal for both cool and warm-season grass. For cool-season grass such as perennial ryegrass, fescue grass, or Kentucky, you can apply Milorganite at least 4 times a year. It is recommended to use this fertilizer when the grass is growing vigorously.

While for warm-season grass, apply this fertilizer late in spring when the temperatures are above 70 degrees Fahrenheit. During this time, the grass is actively growing and requires sufficient nutrients to maintain its green color.

Advantages of using Milorganite Fertilizer on Lawn

Since Milorganite is a slow-release fertilizer, it releases nitrogen, phosphorus, and iron into the soil slowly for a longer period of time, as the plants require. It can last in the soil for up to 10 weeks.

Being organic fertilizer, it improves the health of your lawn as well as that of the soil. It’s also environmentally friendly. It does not contain chemicals that pollute underground water or streams.

The excessive application does not burn your grass, thanks to its low salt content. You do not want to have patches or discolorations of burnt grass in your garden.

Disadvantages of using Milorganite on Lawn

Milorganite is a slow-release fertilizer; it takes a couple of weeks to show positive changes after application. If time is of the essence, this is not the best supplement to choose when you want fast results. Its high nitrogen content also promotes faster growth that requires frequent mowing.

Can I use Milorganite and Ironite?

You can use either Milorganite or Ironite on your lawn. However, it isn’t a good idea to mix both. Using both of them at the same time is a waste of nutrients. Excess iron can also pose a risk to both the environment and plants. You do not want to risk burning your lawn or polluting the ecosystem.

To choose the best product, it is recommended to conduct a soil test. It helps to determine the exact nutrient that is lacking in your soil and the proportions needed. For iron deficiency, soil tests suggest the product to use and the amount needed.

Also read: Best Time to Fertilize a Lawn – Before or After Rain?

Final Thought

Milorganite and Ironite contain iron and other nutrients that promote greener growth. Unlike Ironite, which is used to treat iron deficiency, Milorganite is a slow-release fertilizer that helps plants attain deep green color and strong root development.

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