Rain works to dissolve Milorganite fertilizer and pull it down into the soil. Without water, your Milorganite will not break down and feed your lawn. So, rainfall, after you apply Milorganite, is exactly what your lawn needs. That said, too much rain can be a detriment. If you are expecting more than 1 inch of rain, such as in a storm or multi-day downpour, it may wash your Milorganite away before it can be absorbed. If heavy rainfall is in the forecast, wait to spread Milorganite after the storm passes.
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What Happens if it Rains After You Fertilize Your Lawn With Milorganite?
In most cases, rainfall, after you spread Milorganite, is the necessary step that activates your fertilizer. Dry Milorganite granules resting on the surface of your yard won’t feed your lawn at all. Water must be applied to dissolve the Milorganite and carry it into the soil, where the nutrients in the fertilizer can then be taken up by the grass roots.
- If you receive 1/2–1 inch of rain after spreading Milorganite, it will dissolve the fertilizer granules and pull them into the soil to feed grass.
- If you receive more than 1 inch of rain, the soil can become oversaturated. Milorganite may be dissolved and carried away as runoff instead of absorbed by the soil.
A standard rainfall is usually just what you need to dissolve your Milorganite. In rare cases, heavy storm systems can bring too much rain and work against your fertilizer applications.
How Much Rain is Too Much for Milorganite?
If you receive more than 1 inch of rain at one time there is some risk that Milorganite will be washed away rather than absorbed by the soil. This is caused when the soil is saturated with so much water that it can’t absorb any more. After this saturation point, the water will run off your lawn and into the gutter.
- Heavy rainfall can oversaturate soil with water, causing excess water (and dissolved Milorganite) to run off your lawn and be wasted.
- Over 1 inch of rain can wash Milorganite off of easily saturated soils, such as clay.
- Sandy or loamy soils will typically still absorb fertilizer even if you receive up to 2 inches of rain after spreading Milorganite.
While some loose soil can absorb a lot of rainwater, there is an argument to be made that anything more than 1 inch of rain can be detrimental to your Milorganite application. 2 inches or of rainwater may pull the Milorganite so deep into the soil that nutrients in the fertilizer are carried deeper than your grass roots penetrate. Again, this is a slim chance. In most cases, rainfall after spreading Milorganite is a free way to water in your fertilizer.
Does Milorganite Need to be Watered In?
Milorganite must be watered into soil to be effective. Dry Milorganite granules are loaded with nutrients that feed soil microbes, but they’re useless on top of your lawn. With the addition of 1/2 inch of water, the Milorganite will break down and enter the soil where the organic matter in the fertilizer can be effective.
- Milorganite must be watered into soil to provide benefit to your lawn.
- 1/2 inch of water from rain or a sprinkler is sufficient to water in your Milorganite application.
- The sooner you water in your Milorganite, the sooner it starts providing benefit to your yard.
Watering in Milorganite also has some other pluses. If your pets are drawn to Milorganite and attempt to eat it, simply run the sprinkler and water the granules into the soil to remove this temptation.
Is it Better to Fertilize with Milorganite Before or After Rain?
You can fertilize your lawn with Milorganite both before or after rain. Just follow these tips for best results:
- Spread Milorganite 1–2 days after rain, while the soil is moist but not wet.
- Spread Milorganite when rain is in the forecast. The sooner it rains after application, the sooner the Milorganite will fertilize your soil.
- If extremely heavy rainfall is expected (storms that deliver over 1 inch of water) then hold off on applying Milorganite until after the precipitation has passed.
Milorganite spread on moist ground and watered in soon after will get to work right away, providing iron, nitrogen, and phosphorus to your lawn. This will promote green color, healthy blade growth, and strong turf grass roots.
Is it OK to Spread Milorganite Fertilizer on Wet Grass?
Spread Milorganite on dry or moist grass, but not on turf that is excessively wet. The reason for this is that a very wet lawn may have already reached the soil saturation point. Any water applied after this point will run off the soil. For this reason, it’s best to wait 1–2 days after any rain before you spread Milorganite.
- Milorganite should be spread on dry or damp grass. If possible, do not apply to wet grass.
- A lawn that has recently experienced heavy rain may not absorb dissolved Milorganite—the soil may be too saturated to take on additional water.
- Wait 1–2 days after rain before you spread Milorganite.
Don’t worry if your grass is naturally moist or is damp from morning dew. These conditions are great for spreading Milorganite. The granules will begin to break down faster in moist conditions.
Can You Apply Milorganite Before Rain?
Milorganite can be applied before a rainfall of 1 inch or less. This rainfall will help to water the Milorganite into the soil and put it to work feeding your lawn. Plus, having nature water in your fertilizer is cheaper than running your sprinkler system. If you are due to receive heavy rainfall of over 1 inch shortly after you apply Milorganite, this downpour may wash the fertilizer away. Wait until the storms have passed and the lawn has had a day or two to dry out before spreading Milorganite.