Adding Iron to Your Lawn

I get a lot of emails asking about iron and the lawn. Here is some simple information to help you as you consider an iron application.

Why put iron on your lawn?

ironite lawn additiveAssuming your grass is fairly green and healthy already, you can add a light dose of iron as a way of achieving a richer, deeper blue-green color. This is will surely set your lawn apart in the neighborhood. In fact, it is iron that makes Kentucky Blue Grass, “blue.”

However, iron can also be used to correct soil deficiencies and is considered a viable organic alternative to heavy synthetic nitrogen. (nitrogen gives the lawn a greening but also pushes growth) If your turf grass looks dull yellow, chances are a good dose of iron will help restore it.

What is a good iron additive for the lawn?

You can get DIY iron treatments in liquid and granular form (I prefer granular as liquid is difficult to apply evenly). There are also several quality organic sources of iron available. In most cases, you should look for iron that has been “chelated.”

Long story short, chelated iron has been chemically bonded in such a way as to make the iron readily available for grass plants to use. Minerals are not easily absorbed by plants, and can also be bound up in high pH soils. Using a chelated iron product will get more of the iron into the grass plants quicker for better results.

My favorite iron additive is Milorganite, which is a 100% organic slow release source of chelated iron. In addition, Milorganite contains slow release nitrogenthat works alongside the iron. Another popular iron supplement for lawns is “Ironite.” You can get it at most garden centers.

Some general purpose fertilizers will have a small percentage of iron included as well. Scott’s makes a blend with 2% iron, for example. The problem with these products are that they include way too much fast-releasing nitrogen that will end up pushing unnecessary growth in your lawn.

Negatives to Iron use on the lawn

First off, Ironite, for example, will stain your driveway, brickwork, patio and deck a rusty orange color! There is almost no avoiding this. Once one small pellet hits one of these areas and gets wet, it’s immediately stained. Milorganite, however, does not stain and is more goof-proof.

Secondly, too much iron will turn the lawn a strange dark grey color. If you use Milorganite, you don’t run this risk due to the extreme slow release nature of the product.

When to add Iron to the Lawn

Late spring is the best time to put down your iron treatment. Ideally, temperatures will be between 60 and 70 degrees. NEVER apply iron when temperatures are in the low 80s or higher as this can cause undue stress to grass plants.

I have written article on easy fertilizing techniques that will show you how to apply iron to your lawn evenly. This is important as uneven coverage will cause extreme color variation in your yard.

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Milorganite Organic Lawn Fertilizer Info

The straight poop on Milorganite Organic Lawn and Landscape Fertilizer… I use it on my own lawn, and customer lawns and and it has always delivered quality, safe results. The good folks at Milorganite have not paid me to write about this. I do it to help you!

Buy It Here:

milorganite bagMilorganite is an organic nitrogen fertilizer produced by the Milwaukee Metropolitan Sewerage District in Milwaukee, Wisconsin. Popularized in the United States during the 1940s and 1950s, it consists of processed sludge from the Milwaukee Metropolitan Sewerage District Jones Island Waste Water Treatment Plant. It’s name comes from the combination of “Milwaukee,” “organic” and “nitrogen.”
Milorganite contains microbes that have digested nutrients from the sewage stream along with added iron, used to strip phosphorus from the waste water flowing into Lake Michigan.
That’s right friends, this 100% organic fertilizer product is processed poop! But man does it offer a lot of benefits:

Milorganite benefits:

  1. Adds natural nitrogen to your lawn slowly: Milorganite contains 6% nitrogen in natural, biosolid form. This means nitrogen is released slowly and will not burn the lawn or ruin the soil like synthetic nitrogen fertilizers can. Milorganite is “goof proof,” meaning you can’t burn your lawn even if you put down too much.
  2. Contains micronutrient iron: Milorganite also contains significant amount of iron. For those who are not aware, iron is what makes Kentucky Blue Grass “blue.” However, adding iron to lawns using synthetic products adds a major risk of concrete staining. Milorganite’s slow-released iron will not stain your concrete or masonry work.
  3. Acts as a Deer Repellant: It’s not been scientifically proven, but many sources sware that milorganite placed around trees and shrubs will keep deer away. In addition, your plants will benefit from the nutrients.
    Milorganite is organic: if you are looking to use products in your lawn and landscape that are more environmentally friendly, then Milorganite is a good choice. It won’t burn your lawn or leach into the groundwater like overly-applied synthetics can.

Some drawbacks to Milorganite

  1. You have to put down a lot of it: Some people are put off by the large amounts of Milorganite that you must put on your lawn to get results. It is recommended in Spring time to put down 17 pounds per 1,000 square feet of lawn area. This is compared to synthetic fertilizers where the recommended amount is less than 1 pound per 1,000 square feet. Remember, organics are not as concentrated as synthetic fertilizers.
  2. There is a smell to it: Some people are really put off by the smell of Milorganite (deer too apparently) as it is made from processed sewage. In my personal opinion, the smell is not any worse than any other garden smell and it’s gone in a couple days.
  3. Milorganite does not break down in cool weather: Since it is organic, Milorganite requires heat to release nutrients into the soil so it does not work well in early Spring and late Fall.

What about the heavy metals?
I am no chemist, but some people over the years have warned that Milorganite releases high amounts of heavy metals such as zinc, copper and arsenic into the soil. I’ve combed their website and they claim that Milorganite metal levels are no more than any other fertilizer product on the market today. I believe them!

The best time to apply Milorganite to your lawn is late April as this is the time when temps are rising. If you decide to use Milorganite as your organic lawn fertilizer choice, you will probably only to need to apply it 3 times per year as it is a slow release product.
I recommend applications of 17 pounds per 1,000 square feet in April, June and September.


Final Note: Milorganite is also a great source of slow-release iron for your landscape perennials. If your woody ornamentals or soft perennials have yellowed leaves, milorganite will help restore an iron deficiency.