Fertilizing your lawn and garden is an important step towards ensuring lush green grass and blooming plants. Think of fertilizer as food that will help your grass and plants grow big and strong. It gives them an added boost of important nutrients such as potassium, phosphorus, and nitrogen. Granular fertilizers are easy to spread evenly, but how long does it take granular fertilizer to work?
The Importance of Fertilizing Your Grass
Fertilizer is an important part of lawn and garden care. Helping your plants grow bigger and stronger means that they are better able to withstand adverse conditions.
Longer roots can help grass thrive during summer heat and drought conditions, and it can prevent damage from foot traffic as well.
Thicker and greener grass foliage is also more aesthetically pleasing. Often, fertilizer can give plants the boost they need in order to spread to fill in bare patches and grow a dense canopy that will naturally crowd out weeds.
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So How Long Does it Take Granular Fertilizer to Work?
The short answer is: It depends.
Synthetic and organic fertilizers work a little bit differently from one another. Synthetic fertilizers work quickly and can produce visible results within days. Slow-release organic fertilizers offer slower results that tend to endure.
In this article I’ll get into details about each type, and give you a better idea of when you can expect to see results after using different types of granular fertilizer on your lawn.
Organic Granular Fertilizer
Organic lawn fertilizers tend to be more environmentally friendly than synthetic fertilizers which are made in a lab.
They are composed of organic matter such as bone meal, blood meal, or fish emulsion. What makes them a bit better for the environment is that they don’t create harmful chemical runoff that can then affect local bodies of water or the underground water table.
Why Do Organic Fertilizers Take Longer to Work?
Organic fertilizers have to decompose in order to release their nutrients, so they are known for being more of a slow-release fertilizer.
How long it takes granular fertilizer to work can vary depending on which organic materials were used to create it. Generally, they break down over a period of around two to six weeks.
However, they last far longer and can continue nourishing your plants for months or even years. This means they carry the advantage that they can be applied much less often than a synthetic fertilizer.
Once an organic fertilizer decomposes, it will release the potassium, phosphorus, and nitrogen that will support your plants. They also contain potash, micronutrients, and even microorganisms that are beneficial for your soil.
An interesting type of organic granular fertilizer (and one I use on my lawn 4 times annually) is Milorganite, produced by the Milwaukee Metropolitan Sewerage District. It is actually produced via a process of sewage recycling. It is slow-release, so you won’t risk burning your grass with too much nitrogen. Milorganite also claims that you can see results as soon as one week after application (though I usually notice results closer to 10 days after application).
Milorganite can take up to ten weeks to completely break down. Applying it four times a year is recommended by the manufacturer. That’s what I do to support my lawn in a natural way that’s kid and pet friendly.
As the fertilizer breaks down over that two to five weeks, you will notice that your grass starts to get greener first. Then you will notice a surge in growth a few weeks out from the application.
If you don’t notice any changes at all by around the third week, then you may want to double-check that you applied it properly.
Synthetic Granular Fertilizer
A lot of people automatically think synthetic inherently means that something is bad.
That is not necessarily true of synthetic fertilizers.
They certainly have their own appropriate place on the market. One of the main advantages of a synthetic fertilizer is that the nutrients are readily available without needing to wait for decomposition. This means that your grass or plants get an immediate serving of potassium, phosphorus, and nitrogen.
You can expect to see results as soon as just two to five days after application!
What’s in Synthetic Granular Fertilizer?
The vast majority of these fertilizers have a high nitrogen content and virtually no phosphorus and potassium. This is because nitrogen is what causes the grass to be so richly green. Nitrogen is an essential component of chlorophyll, which is in itself a green pigment. Chlorophyll, in turn, is an essential part of photosynthesis, which helps plants convert sunshine into energy. This is why nitrogen both makes your grass greener as well as helps its leaves grow.
Granular synthetic fertilizer requires water in order to become soluble enough for plants to absorb it. It won’t do much if it just sits there in dry pellet form.
The best time to apply synthetic granular fertilizer is before an anticipated light rainfall (a heavy rainfall and you’ll lose a lot of the value of the fertilizer through run-off). Simply watering the lawn after applying the fertilizer also does the trick. Watering the lawn a few days beforehand to ensure that it is not too dry can also help the soil properly accept the fertilizer.
There are different ratios of nitrogen, phosphorous, and potassium in synthetic fertilizers depending on the climate you are living in as well as what time of year you are applying it. Grass, in particular, has different needs in the Fall as compared to the Spring.
In this way, you can kill two birds with one stone (feed grass while blocking weeds).
There are also varieties with grass seed and synthetic fertilizer called “seed and feed” since fertilizer is an essential component when laying new grass seed.
These variations aren’t seen as frequently in organic fertilizers.
The Synthetic Fertilizer I use on New Lawns and in Spring
I primarily use organic fertilizer on my lawn, but when I’m re-seeding or over-seeding an area, and sometimes if I’m fertilizing just as the soil comes to temperature for new growth in the spring I use this Scott’s product which contains a quick-release synthetic fertilizer and crabgrass preventer.
It works really well and unlike some pre-emergents it does not prevent new grass seed from germinating.
Comparison Between Granular Fertilizers
Organic fertilizers have added benefits such as micronutrients, potash, and microorganisms that are good for your soil. Synthetic fertilizer does not have these other components because it is a chemical fertilizer.
This is also a drawback of synthetic fertilizers as these chemicals are often poisonous. They can often be harmful to the environment when they end up in rainwater runoff that flows to bodies of water or seeps into the water table.
Ensure that the forecast does not call for heavy rainfall that might wash away the fertilizer.
Also, keep children and pets off of a freshly fertilized lawn until 24 hours after it has dried.
How long it takes for granular fertilizer to work depends largely on the type of fertilizer you use.
Synthetic fertilizers work far more quickly than organic fertilizers.
This is due to the need for organic fertilizers to decompose. The byproducts of the decomposition are what actually fertilize the soil.
Thus, someone looking for a quick boost or green-up will benefit more quickly from a synthetic fertilizer.
Why I Primarily Use Organic Granular Fertilizers
There are basically two schools of thought when it comes to using granular fertilizer on lawns:
- Feed the Grass, or
- Feed the Soil
Synthetic fertilizers feed your grass and provide fast, visible results, which is why many homeowners use them.
But what happens over time is that your grass will begin to depend upon those synthetic fertilizers, and when you don’t use them and deny your grass its “fix” of nutrients, your lawn will struggle.
After a season of supporting and feeding the soil in your yard with organic fertilizer, you’ll notice that even if you skip or delay an application, your grass is strong, green, and resilient. That’s because your soil is great.
After years of supporting my yard’s soil with organic products I test my soil using this kit from Amazon every spring, and use that as a guide for the year ahead. I learn what my soil needs (and doesn’t), and I can provide the nutrients my lawn needs to thrive, adjust the pH to unlock the nutrients that are already there, etc.
When to Use Fertilizer for Best Results
The chemical nature of synthetic fertilizers mean they are more likely to burn your grass if over-applied.
This can be avoided by following the instructions on your product’s bag. Ensuring the lawn is properly watered, and spread fertilizer in the early evening on cooler days. Also, make sure that you evenly cover the ground with fertilizer.
Fertlizer can burn dry lawns if applied on hot sunny days. That being said, even organic fertilizer is not completely without its risk of burning (although I don’t have any issues with Milorganite), so it is important to be mindful of the above.
How Often to Apply Granular Fertilizer
I recommend applying fertilizer four times annually, whether you use Milorganite or Scotts or a different brand altogether.
You may need to apply synthetic fertilizers more frequently than that.
Organic fertilizers improve the quality of your soil over the long run. This means their effects are long-lasting and can be noticeable for months or even years.
Watering your lawn prior to application will benefit both types of fertilizer. Watering within a day or two of the application is also essential, whether by rain or sprinkler.
Wait until 24 hours after the lawn dries before letting kids and pets into the fertilized area. You don’t have to wait if you’re using an organic product.
Final Thoughts About Seeing Good Results from Granular Fertilizer
Picking the right fertilizer for your needs will help you achieve your lawn and garden goals. Whether you go synthetic or organic, each method has its own set of advantages and disadvantages.
The speed with which you see results is only part of the story.
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