Three Easy Steps to Determine the Earliest You Can Apply Milorganite in Spring
- Milorganite AgronomistApril 5, 2025
Guidelines are just that: guides. Milorganite offers an annual fertilization schedule for both cool-season and warm-season grasses that’s been dependable for decades. However, many homeowners who are dedicated to caring for their lawns aren’t satisfied with generalities. They want precision. In only three simple steps, you can quickly and precisely determine when you can first apply Milorganite in spring and how much. All you need is your zip code.
Step 1: Determine What Type of Grass You Have
The first step to narrowing down the earliest you can apply Milorganite in spring is to determine what variety of grass you have in your lawn.
There are two categories into which grass is divided: cool-season and warm-season. The map below shows the broad swaths across the country where Northern, cool-season grasses and Southern, warm-season grasses grow. There’s also the “transition zone” between the two, stretching across the middle of the country in which either cool-season or warm-season grasses may grow, depending on the local climate.
Cool-season and warm-season grass varieties are best fertilized on a slightly different schedule, which is why it’s important to first identify the grass variety. The seasonal maintenance of cool-season and warm-season grasses also varies.
Cool-season grasses include Kentucky bluegrass, Fescue, and Perennial Ryegrass, and should be fertilized four (4) times per year.
Warm-season grasses include Bermuda, St. Augustine, Centipedegrass, and Zoysia, and should also be fertilized four (4) times per year. There are two exceptions. Centipedegrass and Bahia grass does best with only spring and summer applications.
If you need assistance identifying the grass variety in your lawn, contact your local University Extension office in your state.
Step 2: Air and Soil Temperatures Determine the Soonest You Can Apply Milorganite® in Spring
Lawn enthusiasts often want to know more precisely when they can start fertilizing spring. There’s an easy way to figure that out, and all you need is your zip code!
In spring, Milorganite should be applied after the last frost and the turf is beginning to break dormancy and turn green. This applies to both cool-season and warm-season grasses. The Old Farmer’s Almanac offers an interactive map you’ll find helpful. Just enter your zip code and it provides the average last frost in spring and first frost in fall.
Optimum Air and Soil Temperature Ranges
For cool-season grasses, Milorganite can first be applied when daytime temperatures are regularly in the 60s and soil temperatures average in the mid-50s.
Warm-season grasses require temperatures that are slightly higher than cool-season grasses before fertilizing. Air temperatures for warm-season grasses should consistently be in the 70s and soil temperatures in the 60s for optimal spring application.
It's easy to monitor air temperature, but what about soil temperature? That’s where your zip code comes in.
Here’s a handy soil temperature tool you can use to determine the current, 24-hour average, and 5-day average soil temperatures. Just enter your zip code, and you’ll have the information to precisely determine the earliest possible time in spring to apply Milorganite.
If you’re not interested in being this precise, that’s okay. It’s easy to remember when to fertilize using our “holiday schedule.”
Schedule to Fertilize Cool-season Grasses
- Memorial Day/mid-to late-May
- July Fourth/Canada Day
- Labor Day/early September
- Thanksgiving/mid-November
Schedule to Fertilize Warm-season Grasses
• Easter/after turf breaks dormancy
• Memorial Day/mid- to the end of May
• Labor Day/early September
• Early October
Step 3: Now I Know When I Can First Apply Milorganite® in Spring. But How Much (Milorganite) Should I Apply?
Established lawns should apply 32 lbs. of Milorganite per 2,500 sq ft for both cool-season and warm-season grasses.
Always familiarize yourself with local ordinances to identify additional fertilization restrictions and blackout dates. Contact your local University Extension office in your state for additional fertilizer application information specific to your area.
Milorganite Application Tips
Here are additional tips on applying Milorganite fertilizer to your lawn anytime.
- Mow before you apply Milorganite for improved fertilizer/soil contact.
- Use the correct type of spreader and spreader setting to learn how you can easily calibrate any spreader.
- Although not required, watering in Milorganite can ensure better fertilizer contact with the soil and can speed up the process of microbes breaking down Milorganite. Synthetic-based fertilizers can burn turf if it remains on the surface of grass blades, which is why they always need to be watered in.
- Apply half of the recommended amount of Milorganite in one direction and the other half in the opposite direction to help ensure even coverage.
