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What Are The Numbers On Lawn Fertilizer

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What Do The Numbers Represent

What do the Numbers on Fertilizer Mean?

The three fertilizer numbers on the label of every bagged or bottled fertilizer show the N-P-K ratio.

The N stands for nitrogen, the P for phosphorous, and the K for potassium in a specific balance.

These fertilizer numbers represent the percentage of the three macronutrients found in that package. Plants use several nutrients to fuel their growth, but the N-P-K ratio is the most crucial.

A pack of fertilizer with the fertilizer numbers 10-5-10 on the label, for example, contains 10% N, 5% P, and 10% K. The remaining 75% of the carrier product makes up the bags weight.

The initials SR after the numbers stand for Slow Release. Instead of being immediately available to the plant , the fertilizer is released regularly over time.

A slow-release fertilizer reduces the need to reapply it. You can also use this fertilizer on a more regular basis.

The three significant macronutrients above are just the beginning.

Plants also require other nutrients to thrive. These nutrients are known as micronutrients. Magnesium, calcium, and iron are other essential nutrients for garden health, and a lack of these might cause plant weakness.

Putting your soil through a test is the only way to know what your soil contains or does not include precisely. However, if you examine your plants more closely, you may be able to detect some shortcomings on your own.

The Best Lawn Fertilizer Ratio Gives Your Lawn The Nutrition It Needs

As weve seen here, fertilizer can be an essential part of providing your lawn with essential nutrients.

While there are certain N-P-K ratios that are suitable for most lawns, there are certain circumstances in which you might want to use something different, which is why I recommend every homeowner invest in a reliable soil test each spring.

Understanding what the function of each nutrient is for your lawn will allow you to watch out for signs of deficiency.

And remember, too much of a good thing isnt good for grass, so before you just spend a few hundred dollars on fertilizer for your property, make sure you know whats already in the soil. Often unlocking the potential thats already there is cheaper, and better for your grass.

Why Are These Numbers So Important

Now that we understand what these numbers mean, it is important to see how all these numbers work and why you should care. All plants need all three of these nutrients to grow. Without enough of any of them, the plant will end up failing. However, each plant will need different concentrations and ratios of these nutrients which is why the numbers on the package are important.

Each nutrient is responsible for helping out a different part of the plant. For example:

Knowing the right NPK values of any fertilizer you would like to use helps you select one that is best for any plants you would like to grow. For the leafy vegetables, you need to choose a fertilizer that has higher concentrations of nitrogen to promote the growth of the leaves. If you have flowers, then a higher phosphorus concentration is better to encourage the blooms.

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What Is 10 20 20 Fertilizer Used For

One of the most common combinations of these components is 10-20-20. This is a general purpose fertilizer thats best applied to vegetable gardens. Its specially recommended for root vegetables and beans.

But this fertilizer isnt recommended for lawns because it doesnt contain the ideal balance of nutrients needed for new grass seedlings or established grass. Instead, you should use a more specialized fertilizer for your lawn.

What Do The Three Numbers Tell Us

what do the numbers on fertilizers mean

All fertilizer companies denote the ratio of the NPK elements in their product in this three-number pattern. It indicates the percentage of NPK like for instance a 10-20-10 ratio says that a 100-pound bag of fertilizer contains 10 pounds of Nitrogen, 20 pounds of phosphorus, and 10 pounds of potassium of which totals up to 40 pounds of nutrients. The remaining 60 pounds will constitute filler such as sand, rice hulls, or perlite.

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Fertilized After Winter Dormancy

Lawns in Denver are starting to green up and if you have not fertilized your yard, its time. After winter dormancy and a dry winter, your yard may be hungry. Fertilizer is food for your lawn and the last time it had any nutrition was probably last fall. Cool season grasses like to fill in this time of year and an application of fertilizer goes a long way to improving your root system and filling in weak spots. Spring fertilization will set your yard up for summer. Your lawn gets nitrogen from rain and snow. After a dry winter, give your yard some nutrition. Have a look at your yard and rate it. Good condition , OK condition , or Poor condition . Now, lets talk about fertilizer.

Fertilizer Numbers What Do They Mean

by Clint Baxter | May 8, 2015 | Fertilizing my lawn |

When I think of fertilizer numbers, I think about the good ole days when buying a bag of fertilizer was pretty simple. There were very few choices and the prices were reasonable. Now days, there are dozens of choices available from our local retailers. Prices are higher than ever due to the fact that everything we buy is related to the price of oil, including the fertilizers we buy for our lawn.

During my career as a garden center employee, Id often have an old-timer come in and ask for Triple 13. Now Im not talking about some fancy casino slot machine game! Triple 13 or 13-13-13 refers to the nutrient analysis in that particular bag of fertilizer. The three numbers represent Nitrogen , Phosphorus and Potassium . These are the 3 macro-nutrients that make up a bag of fertilizer sold for the purpose of feeding your lawn.

The first of the fertilizer numbers is Nitrogen . Nitrogen is the key ingredient for feeding your lawn. It is what promotes the growth of everything you see above ground. Frequent Nitrogen feedings will maintain healthy, consistent growth in a high quality lawn. Generally, the bags of fertilizer that you buy will have more nitrogen in them than any other nutrient. Nitrogen also is the quickest to get used up by the grass.

Now there are secondary macro-nutrients and even more micro-nutrients that used in a bag of fertilizer and you can read about them my blog post What nutrients does my lawn need?

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Is 16 16 16 Fertilizer Good For Lawns

As the combination suggests, the 16-16-16 fertilizer is a balanced combination of Nitrogen, Phosphorus, and Potassium, all of which are important to increase the soils nutrient levels. You can use this fertilizer for almost all types of plants.

You can use it for flower beds, lawns, ornamentals, vegetable gardens, and trees although flowering plants will benefit the most from it. Although its not considered the best fertilizer for lawns, you can still use it to rejuvenate the nutrients in the soil.

When Your Grass Roots Are Actively Growing

Lawn Fertilizer NPK Numbers

If the grass looks greener on the other side of the fence, its because they take better care of it. Cecil Selig

Lend Mother Nature a Hand Mother Nature has her ways of naturally fertilizing your lawns soil. For example, did you know that during lightning storms, nitrogen atoms are released which are then absorbed by the rain, and when the rain hits your lawn, the nitrogen goes into the soil and your lawn is fertilized? There are at least 17 essential nutrients required for plant growth. Plants get these nutrients from the air, soil and water.

Typically, even with Mother Natures best efforts to REPLENISH these nutrients, your lawn still needs help from you to be lush and green. Commercial fertilizers contains many of the nutrients that nourish your grass as it grows, including the 3 nutrients at are most crucial to plant growth:

  • Nitrogen
  • Phosphorus
  • Potassium

On bags of store-bought Fertilizer, you always see 3 Numbers that represent the N-P-K Rating. If you want to learn more about these N-P-K numbers, check out this Wikipedia article. Basically, each number is the percentage of N-P-K in the fertilizer.

For example, a 50 pound bag of 25-0-10 fertilizer is made up of:

Cool Season Grasses vs. Warm Season Grasses

Q: What type of Grasses are best suited for the climate here in Indiana? A: If you guessed Cool Season Grasses, you are CORRECT.

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How Can This Save You Money

Look at the current status of your lawn.

AN ESTABLISHED LAWN:needs primarily nitrogen, since it is not producing any fruit or flowers, so get Big – Small – Small. Nitrogen is the least expensive of the nutrients. Dont buy a formula that has high levels of phosphorous or potassium when you dont need them.


is special and needs more phosphorous to produce roots. Dont use high nitrogen because the roots are not ready to handle top growth. Go with Small – Big – Big. Phosphorous and potassium are more costly, so you would not use this all the time. Yet, investing in the more expensive list of ingredients for a new or damaged lawn is wise.

NEW SOD:Be safe when you fertilize new sod! It looks like a mature lawn, but the roots have been shaved off and it needs to recover. Save the expense of redoing this huge project. You can kill the young lawn with the wrong blend. Avoid stress and later expensive problems by helping the grass get established properly. Use Small – Big – Big or Zero – Big – Big.

A STRESSED LAWNfrom many conditions, like recovering after insect damage, preparing for winter or extreme heat needs more potassium. Try Big – Small – Medium or Big – Small – BigWhen the grass has stressful conditions to deal with, applying the more expensive potassium can prevent problems from developing or continuing. Pay now and dont pay later.


What Are The 3 Numbers On Fertilizer

Many garden enthusiasts are already familiar with the 3 numbers that appear on the packaging of fertilizers. These numbers show the nutritional value for plants of each product.

These are the fertilizers NPK numbers and they represent the 3 most important nutrients Nitrogen , Phosphorus , and Potassium that plants need. There are around 16 of these essential nutrients but these 3 macronutrients are the most important. Knowing the meaning of these numbers will help you choose the best fertilizer for your plants.

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Is There Really A Best Lawn Fertilizer Ratio

Yes, there is an ideal ratio of fertilizer for most lawns. The ratio of nitrogen , phosphorus , and potassium in a fertilizer is the N-P-K ratio. The ideal lawn fertilizer ratio for most lawns is 3:1:3 or 4:1:2, but every lawn is unique and evaluating your soil with an accurate soil test kit is the best way to understand exactly what your lawn needs and unlock the full potential of your yard .

The Benefits Of Phosphorus

fertilizer 29 3 4

The second number represents the percentage of Phosphorus.

Phosphorus is critical in developing and strengthening a healthy root system of turfgrass. If only Nitrogen is applied to the lawn, the grass will be nice and green, but as watering or a drought hits the grass will be greatly impacted. Having strong roots in your grass will keep your lawn healthy through the changing weather and stresses of the seasons.

Phosphorus or P is a primary plant nutrient that is involved in the metabolic processes responsible for transferring energy throughout the plant. Its crucial to introduce phosphorus when first establishing turf grass and continue application as the grass grows. An abundance of phosphorus allows plants to grow more efficiently.

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What Does Npk Mean

The NPK expands for Nitrogen, Phosphorus, and Potassium, where N stands for Nitrogen, P for Phosphorus, and K for Potassium as these abbreviations are the chemical notations of these elements.

  • Nitrogen Nitrogen is a really important nutrient for the lawn as it provides the grass with the food to grow. Nitrogen is the main nutrient behind the green color of the leaves as it helps in making chlorophyll. This is the main reason you will find all the fertilizer with a high percentage of nitrogen to give the lawn a boost and healthy growth throughout the year.
  • Phosphorus Phosphorus is another nutrient that is really important for the lawn as it helps the plants to establish themselves in the soil by promoting root growth. This makes the grass hardy and faces the long and hot days of summer and sometimes drought because of the deep root system.
  • Potassium Potassium is a nutrient that helps the plant fight diseases and keeps the lawn healthy and thick. Potassium also helps the grass in boosting the process of food making and helps in absorbing water which makes it easy for the grass to grow.

Should I Mow Before Fertilizing

Ideally, youll want to mow and rake before fertilizing, so that excess lawn waste is removed and the fertilizer will have an easier time reaching the soil. Aerating your soil before fertilizing can also help the best times to aerate are when your grass is actively growing, such as in spring or early fall.

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What Fertilizer Numbers Mean:

There are three numbers in the form of N-P-K on a fertilizer bag which represent the main elements found in the fertilizer.

N represents the Nitrogen % content in the bag.

P represents the Phosphorus % content in the form of phosphate .

K represents the Potassium % content in the form of potash

These numbers are commonly referred to as the nutrient analysis of the fertilizer. For example, a 4-4-4 fertilizer would contain 4% N, 4% P, and 4% K. Depending on your planting needs, you may need varying amounts of the above nutrients.

Why Should You Test Your Soil

What Do The Numbers On Fertilizer Bags Stand For?

You should test your soil to find out its pH level and any nutrient deficiencies. Testing your soil will help you better understand what kind of fertilizer you need for your soil.

If you find that you have a deficiency in one of the macronutrients or micronutrients, use a fertilizer that will help you solve this problem and create a well-balanced, nutrient-dense environment for your lawn to thrive.

Soil Test Kits Ive Used & Recommend

There are many options for testing your lawns soil, but I prefer a lab-based soil test that will provide a detailed analysis of your soils nutrients and what it needs for your lawn to thrive.

And if youre interested in taking the guesswork out of what to do next after you get your soil test results, consider subscribing to one of LawnServs subscription boxes. Theyll test your soil and curate the products your lawn needs, mailing them to you with everything you need . Its pretty fool-proof .

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How Do You Adjust A Fertilizer Spreader

Adjusting your fertilizer spreader or calibrating is the right way to get the best out of your spreader for even application. To do this there a few steps you would have to follow and we will explain them:

  • The first step in calibrating your fertilizer spreader is to calculate the amount of fertilizer needed per 100 sq ft. This is done by dividing 100 sq. ft by the square ft area the fertilizer is supposed to cover.
  • The number obtained from this is then divided by the weight of the fertilizer bag. For example if the fertilizer is supposed to cover a total area 5,000 sq. ft and the fertilizer bag weighs 25lbs then it will be: 25 lbs x = 0.5lbs
  • This means that 0.5lbs worth of fertilizer is to be applied for every 100sq. ft area. This amount is placed in the spreader.
  • For broadcast spreaders, it is advisable to start off with a 10ft x 10ft area which is 100 sq ft. For drop spreaders however the required length is determined by the width of the spreader.
  • Apply the fertilizer using the suggested setting.
  • However if the fertilizer is used up before you completely cover the area, decrease setting and then start off on another 100sq feet until the correct amount setting is achieved.
  • Also if the fertilizer remains after the area has been covered up, increase the setting and then start off on another 100 sq feet until the correct amount needed is achieved.

Why Is Phosphorus Important For Your Lawn

Phosphorus is essential for root growth. It is especially crucial for early grass development and a lack of Phosphorus could be why youre having trouble growing a new lawn from seed.

Phosphorus keeps your grass healthy, especially early in its life. The stage of life at which phosphorus is most important for your grass is when it is young and still establishing its roots and growing new blades of grass.

Phosphorus continues to be important even with established lawns because it maintains lushness and thickness. When the roots of your grass are healthy, they are more effective at absorbing nutrients and maintain strong growth. Your lawn will also be more resilient to drought.

If you want your lawn to be thick and soft, phosphorus is a key component of the best lawn fertilizer ratio.

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