Milorganite, an organic nitrogen fertilizer, is a product that you’re likely to consider using on your lawn. That’s because you can apply it without risk of burning your grass. Also, it contains a iron, which means when you apply Milorganite it will help grass achieve a beautiful dark green color. But you may wonder when to use Milorganite on your lawn to achieve the best outcome.
In this article I’ll explain the best schedule for Milorganite application so you can maximize the benefit of this incredible organic fertilizer without wasting money by applying it too frequently.
This article was last updated on by Lawn Chick Owner Sarah Jameson
Article content reviewed for accuracy by Certified Horticulturist Nicole Forsyth, M.S.
Jump Right to the Milorganite Schedule
I’ve got lots of good info in this article and hope you read the whole thing, but if you’re just here for a Milorganite application schedule, I’ve got you … you can skip ahead right here:
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What is Milorganite?
Milorganite is an organic fertilizer for lawns and gardens which is manufactured by the Milwaukee Metropolitan Sewerage District.
It’s produced through the treatment of wastewater with microbes. After the end of the process, the clean water that is separated from the product is released into Lake Michigan. The product, which is the microbes left over, are heat-dried, which makes them safe to apply and free of pathogens. This is when they become Milorganite, the fertilizer millions of homeowners around the country apply to their lawn.
Thank you, kind people of Milwaukee!
It’s common for gardeners to be concerned with Milorganite’s safety. After all, it’s manufactured from wastewater. Luckily, there’s nothing to worry about, and in fact the ability to safely reuse wastewater in this way is pretty revolutionary.
The meticulous process of production involves the microbes being dried under tremendously high temperatures of between 900 and 1,200 degrees Fahrenheit. This dries out the microbes, destroying all of the pathogens, making it one of the safest organic fertilizers to use on your lawn or in your garden.
After the drying process, there is a careful testing process to make absolutely certain that Milorganite is safe to use and won’t cause any human health concerns. It is held to the standards of the U.S. Environmental Protection Agency.
Milorganite Application Rate and Schedule
The manufacturer of Milorganite fertilizer recommends specific application rates and schedules. It’s important to be aware of these, as if you don’t abide by the instructions, you’re unlikely to achieve the best possible results for your property.
When deciding on an application schedule and finding out how much Milorganite fertilizer you should apply, you must consider the species of grass you have and where you live.
One general rule of thumb is that you should use a single 32-pound bag for every 2,500 square feet of lawn.
How Many Bags of Milorganite per Acre?
This table is based on the manufacturer’s recommended application rate of 2,500 square feet per bag.
| Yard Size | Bags of Milorganite* |
| 2,500 sq feet | 1 |
| 1/4 acre | 5 |
| 1/3 acre | 6 |
| 1/2 acre | 9 |
| 2/3 acre | 12 |
| 3/4 acre | 13 |
| 1 acre | 18 |
Keep in mind that if you have a 1/3 acre property, your house, driveway, and gardens occupy some of your lot’s square footage, so you probably won’t need 6 full bags for your property.
How Many Times per Year Should You Apply Milorganite?
Generally, you should fertilize four times annually. If you choose to fertilize only once a year, though, early fall is the most appropriate time as you’ll provide your lawn with plenty of nutrients to bounce back strong after a long winter.
Now let’s get a little more granular about when to use Milorganite in different parts of the country and on different types of lawn.
RECOMMENDED: The Fall Lawn Fertilizers I Recommend
Warm-Season Grasses in the South
If you live in the south it’s likely that you have a warm-season grass such as Zoysia, Bermuda, Bahia, St. Augustine, or Centipedegrass.
In this case you will want to fertilize with Milorganite four times every year for best results.
The exception for southern lawns is if you have Bahia or Centipedegrass.
If your lawn is primarily either one of these grass species, you should fertilize in the spring and summer only. You shouldn’t do an application in the fall, as you could run into problems with winterkill in your yard if you do.
You’ll know when to do your spring fertilizing with Milorganite in the south once the last frost has passed and your grass starts to get green and appears to be growing.
When to Use Milorganite on Warm Season Grasses
It’s generally best to apply Milorganite fertilizer to warm-season grass at the following times of year:
- Easter (this should be after the turf comes out of dormancy): The application rate at this time is 32 pounds per 2,500 square feet.
- Memorial Day (the end of May): The application rate at this time is 32 pounds per 2,500 square feet.
- Labor Day: The application rate at this time is 32 pounds per 2,500 square feet.
- Early October (alternatively, when you do fall overseeding): 32 pounds per 2,500 square feet.
The Spreader I Use & Recommend
I’ve owned and used a number of different broadcast spreaders, and if you want the best one available, I recommend The Andersons Yard Star spreader. It is American made, can hold 50 pounds of material, rolls smoothly and easily, and is the most accurate spreader I’ve ever used.
Cool-Season Grasses in the North
Examples of cool-season grasses are Perennial Ryegrass, Kentucky Bluegrass, and Fescue. If your lawn is in the Northeastern US, pacific northwest, or northern half of the midwestern United States it’s likely that you have cool season grasses, which you should fertilize these grasses four times annually.
When to Use Milorganite on Cool Season Grasses
The following are generally the most effective times to fertilize your cool-season lawn with Milorganite:
- Memorial Day (the end of May): The application rate is 32 pounds per 2,500 square feet.
- July 4: The application rate is 32 pounds per 2,500 square feet.
- Labor Day: The application rate is 32 pounds per 2,500 square feet.
- Thanksgiving (second half of November): The application rate is 32 pounds per 2,500 square feet.
Tips for Fertilizing New Lawns with Milorganite Fertilizer
If you want to feed a new lawn with Milorganite, mix it into the top couple of inches of the soil prior to applying your seed.
After your grass seedlings germinate and you’ve mowed your lawn three times, apply two bags (32 pounds each) for every 2,500 square feet of grass. This is 2x the recommended rate for established lawns, but will really give your young grass the nutrients they need to thrive.
After this, follow the application schedule for your grass type / region I outlined above, but continue at 2x the standard application rate for the first year (64 pounds / 2,500 square feet).
Milorganite Fertilizer is a Great Choice for Lush, Green Grass
If you’re looking for a magic bullet that will transform your lawn to make it the envy of your neighbors, give Milorganite a try. It won’t magically cure all of the underlying issues in your lawn (weeds, ants, grubs, and other pests)
It’s this organic nitrogen fertilizer’s high iron content is what makes it so incredibly effective at transforming the look of your lawn. It will feed your grass, and green up your yard without burning your grass.
It’s one of my favorite lawn fertilizers, and you now have all the information you need about how much to apply and when to apply Milorganite to feed your lawn with this organic, sustainable product.
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-Sarah
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