April 29, 2025
Milorganite fertilizer: Why lawn care pros swear by this slow-release organic option
07/02/2025
12 minute read
Key Takeaways
- Milorganite is an organic, slow-release fertilizer that improves soil health while being safe for pets and children.
- Unlike synthetic fertilizers, Milorganite slowly feeds plants, reducing runoff and promoting healthy soil.
- Available in various sizes, Milorganite suits small gardens, residential lawns, and large-scale professional applications.
Maintaining a healthy and green lawn requires more than just watering and mowing. Fertilisers are important because they feed the soil with the necessary nutrients that plants need to grow strong. But many conventional fertilizers are far from perfect; they are often chemical-intensive, causing water runoff and environmental damage. This is where Milorganite comes in, providing a better, greener option for both homeowners and lawn care professionals.
Milorganite has made a resurgence because it is organic and time release. Unlike standard synthetic fertilizers, which can easily wash away and pollute the environment, Milorganite leaches out nutrients slowly, redeeming the soil rather than the earth. Milorganite is the choice of professional lawn care providers as it improves the lawn and garden and reduces long-term soil compaction and run-off.
Milorganite and Its Nutrient Profile
Milorganite is a specific brand of fertilizer produced from heat-dried biosolids, which are sewage sludge that has been processed and treated. This procedure helps ensure that the fertilizer is free from harmful pathogens and is a safe product for lawn and garden applications. Milorganite is a natural (non-synthetic), organic (carbon-based) fertilizer that feeds the plant and soil.
Milorganite nutrients have a balanced N-P-K ratio of 6-4-0. This means it contains:
- 6% Nitrogen (N) which promotes healthy leaf and stem growth.
- 4% Phosphorus (P) which supports strong root development.
- 0% Potassium (K) as it’s not needed in large amounts for most plants.
What makes Milorganite special is that it’s very high in organic matter about 85 percent organic material by weight. This organic material aids in structuring the soil, assisting in water retention and utilizing nitrogen, while also allowing a better environment for microbial activity to take place, so the land is more conducive to growing.
MEET THE EXPERT
- ■ Jaime Staufenbeil, Milorganite’s primary agronomist, specializes in fertilizer application and seasonal lawn care strategies.
- ■ Allyn Hane is a passionate advocate for Milorganite, helping popularize it among DIY homeowners and influencing its widespread adoption.
Milorganite vs Synthetic Fertilizer
Here is a comparison of Milorganite (organic) and synthetic fertilizers:
| Aspect | Milorganite (Organic) | Synthetic Fertilizer |
|---|---|---|
| Source and Composition | Derived from heat-dried microbes in wastewater | Made from chemicals, often petroleum or natural gas-based |
| Release Rate | Slow-release feeds plants over 8–10 weeks | Fast-release, quick nutrient boost, but leaches away quickly |
| Impact on Soil Health | Improves soil structure, adds organic matter, and promotes microbes | Does not improve soil structure; overuse can degrade soil |
| Nutrient Content | Lower nitrogen (6%), includes iron and trace minerals | Higher nitrogen content, often in ratios like 20-10-10 |
| Environmental Impact | Eco-friendly, minimal runoff, uses recycled biosolids | Higher risk of nutrient runoff and water pollution |
| Safety | Safe for pets and children, non-toxic, non-burning | Can be harmful to pets/children if overapplied, may burn plants |
| Cost | More affordable long-term, fewer applications needed | Generally cheaper upfront, requires frequent reapplication |
| Environmental Sustainability | Supports recycling and sustainable practices | Often produced with fossil fuels, less sustainable |
Benefits of Milorganite
Milorganite has some key advantages that make it a desirable choice for both professionals and the average homeowner. Here are the main advantages:
Slow-release Nitrogen
One of Milorganite’s signature traits is that it is slow-release nitrogen. Unlike synthetic fertilizers with nutrients that are absorbed immediately but last only a short time, Milorganite (depending on the temperature) feeds the plants for 8-10 weeks. This gradual constant release prevents the leaching and runoff, keeping the nutrients in the soil longer, always present for the plants to take what they need when they need it. This process also aids in cleaning waterways by reducing pollution which makes Milorganite a sustainable choice.
Non-burning Formula
Non-burning formula makes Milorganite safe to use even in hot weather. One of the things that makes Milorganite so great is its slow-release nature. Many chemical fertilizers can burn grass and plants pretty horrendously especially when it’s hot, but not Milorganite. It’s okay to spray in the heat of summer without fear of damaging the lawn. And people don’t need to have water it in, right after application, as with some fertilizers, which must be wetted to be activated.
Soil Health Improvement
Not only does Milorganite supply essential nutrients, but it also applies organic matter to the soil, which improves soil structure. The organic matter works to improve soil aeration, moisture retention, and drainage, which assists in growing plants. Additionally, Milorganite stimulates microbial activity in the soil creating an ideal environment for growing and nutrient recycling.
Eco-friendly
Milorganite is also an organic fertilizer that reduces the amount of nutrient run-off into the ecosystem. And because it’s derived from recycled biosolids, it removes waste from landfills and repurpose it for the planet. Milorganite decreases the chance of hazardous chemicals washing into lakes and streams, which helps preserve the environment and ecosystem.
Top Picks of Milorganite Fertilizer
When it comes to deciding on which Milorganite fertilizer is ideal for lawn care, people have a number of choices and each one is great for yards smaller or larger and the needs users have for it. Here are three best bets from Growcycle, suitable for small- and large-scale operations.
1. Milorganite 5# 6-4-0
For those with a small garden or special fertilizing needs, the Milorganite 5-pound bag is ideal. This is a compact size that delivers the same slow-release nitrogen formula that runs all the way up to 4 months, just in a bag designed for container plants, flower beds, or spot treatments.
It’s a convenient size for homeowners with smaller lawns, so users can still take advantage of Milorganite’s nutrition-rich product without making a bulk purchase.
2. Milorganite 50# Pro Grade
Ideal for professional users and bulk applications, the 50-pound Pro Grade bag is the all-purpose product for any repair need. It's perfect for landscapers or anyone with a lot of turfgrass or lawn to maintain. Delivering the identical time-released technology, it'll keep feeding while the grass grows thick and strong over time.
The big bag will be more economical for professional users, ideal for looking after a number of properties or larger commercial premises.
3. Milorganite 32# 6-4-0 2500sqft (63/PLT)
For homeowners with average-sized lawns, the 32-pound bag is a great choice. It covers approximately 2,500 square feet, making it suitable for most residential lawns. If you need to purchase in bulk, the 63-bag pallet is a fantastic option for community projects, businesses, or anyone looking for a more cost-effective solution.
This size ensures consistent, slow-release feeding for vibrant, healthy grass throughout the season.
Application Tips for Using Milorganite Fertilizer
Milorganite is a very well known and effective slow-release fertilizer used to keep the lawn looking great by providing the nutrients it needs over time. For best results, proper application of Milorganite is important.
1. Recommended Application Rates
For lawns, Milorganite is typically applied at the rate of 32 pounds per 2,500 square feet. The amount is such that the plant receives nutrients in a slow feeding manner for several weeks. But read the directions on the product label, which can vary according to a lawn’s needs and soil conditions. It is important to follow the application rate to the letter due to the issue of over and under fertilizing the lawn.
2. Best Times to Apply
Milorganite should be applied during growing periods, which means spring, early summer, and fall are the best bet. The highest use periods occur at or around Memorial Day, Independence Day and Labor Day, when most grasses are in their most active growth cycles. By applying the fertilizer during those times, the lawn is able to get the nutrients when it’s actively growing, which will result in a healthier, lusher, greener grass.
4. Consider Soil Testing
It’s beneficial to give the lawn a soil test before adding Milorganite, so users know the exact nutrient profile the lawn needs. It can also be beneficial to perform soil tests to decide if need additional amendments, such as lime to adjust the pH, or if other nutrients might be in short supply. This makes certain that Milorganite is being used as it is most beneficial to the lawn.
5. Use a Broadcast Spreader
For an even application, Milorganite is best spread with a broadcast spreader. This kind of spreader will spread the fertilizer uniformly along the surface of the lawn. Spreader settings on the product bag must be strictly followed for adequate coverage. The overlaying row system prevents missing or over-discharge of fertilizer through the double covering operation.
5. Water After Application
It is important to water the lawn well after spreading Milorganite. Watering triggers the slow-release formula so the lawn gets a regular feeding and a boost of nutrients. It also aids the fertilizer in moving down into the soil and prevents the fertilizer from just laying on top of the grass and not being as effective. Correct watering also makes sure that the fertilizer is absorbed efficiently for better effect.
8. Mow Before Applying
People should also mow the lawn before applying Milorganite. People really need to mow to cut the grass short, so that the fertilizer comes into direct contact with the soil. This allows for maximum nutrient uptake and stops the fertilizer from resting on the surface of the grass itself where it is not as effective. A properly mowed lawn provides a level surface to distribute the fertilizer evenly.
7. Apply in Dry Conditions
Milorganite should be applied when the lawn is dry, as applying it during wet conditions can lead to uneven distribution or potential runoff. Dry conditions help the fertilizer settle into the soil more effectively, ensuring that the nutrients are absorbed gradually over time. Avoid applying Milorganite during or right before rainfall, as it may wash away before it has a chance to settle.
8. Reapply as Needed
The lawn should be dry when the Milorganite is applied, as spreading Milorganite on wet conditions may cause uneven dispersion and run-off. When dry, the fertilizer is able to penetrate the soil more and nutrients are released slowly over time. Don’t use Milorganite during or just before a rain; it might wash away before it gets a chance to settle.
Environmental and Safety Considerations
Milorganite is a natural and environmentally-friendly fertilizer that has many advantages for the lawn and the environment.
Compliance with EPA Standards
Milorganite complies with the stringent standards of the Environmental Protection Agency (EPA). When used as a fertilizer product, it’s heated to kill any harmful bacteria in it, making it safe for the environment and people. The EPA has approved the fertilizer for use on food crops, so people can use it safely in gardens where fruits, vegetables or herbs are grown. This makes it an excellent choice for homeowners who wish to keep their lawns and gardens healthy and secure.
Non-Staining Iron
Milorganite includes iron, which facilitates keeping the grass green. Unlike many fertilizers, Milorganite won’t stain driveways, sidewalks or any other paved surfaces. For homeowners who are concerned about the ugly stains that watering and fertilizing the soil can leave on their surfaces throughout their yard. The non-staining formula means the whole property will look clean and well-pruned after use, even the areas where people feed the lawn.
Pet and Child Safety
Milorganite is safe for both pets and children. It doesn’t contain harmful chemicals like some synthetic fertilizers, making it a safer option for families. However, it’s a good idea to keep pets and kids off the lawn for 24 to 48 hours after applying the fertilizer, to give it time to settle. The smell of Milorganite organic lawn fertilizer is safe for pets, so watering the lawn right after applying it can help reduce this attraction. Because Milorganite releases nutrients slowly, it’s also less likely to run off and pollute nearby water sources, making it a safe and environmentally friendly choice.
FAQs
Is Milorganite a slow-release fertilizer?
Yes, Milorganite is a time-release fertilizer. It slowly feeds plants for up to 8–10 weeks so that plants grow stronger and healthier without the risk of burning grass. This controlled-release feature also helps provide the lawn with the necessary nutrients throughout the growing season.
What is the best time to use Milorganite?
Ideal times to apply Milorganite are during the growing season, which includes Memorial Day, Independence Day, and Labor Day. These applications are made when the grass is growing and can grow into the fertilizer that is distributed. People can also use it in the early spring and late fall as part of regular lawn maintenance.
How Milorganite improves soil health?
Milorganite contributes to soil health by adding organic matter and micronutrients that improve the soil’s structure and encourage microbial activity. The organic material in Milorganite improves the soil’s ability to hold on to moisture and nutrients, so the soil becomes more fertile over time. This, in turn, creates a healthier environment for grass and other plants. It will also improve aeration and encourage stronger root production.
The Bottom Line
Milorganite is a very safe and eco friendly slow release fertilizer suitable for the homeowner and the professional landscaper. It's a slow-release product that feeds the grass with a steady supply of nutrients over time, promoting a healthy and vibrant green lawn without the risks associated with synthetic fertilizers. Milorganite not only feeds the soil with organic matter and benefits beneficial microbes, but it also lessens the environmental impact, which is something users should be concerned with.
Growcycle has an extensive range of Milorganite products to allow homeowners the right fit for their lawn. Whether you have a personal garden or a big property, they have bag sizes that range from smaller to bigger so lawn care is easier for everyone.
Disclaimer: This material is for informational purposes only and should not be relied on for legal, medical, financial, or any other form of professional advice.
About the Author
Victor Miller 
Environmental Journalist Focused on Sustainable Agriculture
Victor Miller is an environmental journalist at Growcycle, specializing in sustainable agriculture. With a passion for storytelling, he highlights the latest trends, innovations, and practices that promote ecological balance and responsible farming.
