3 numbers on fertilizer

Fertilizer terms can be confusing. What is the NPK ratio? What are nitrogen, phosphorous, and potassium? Let us take the guesswork out of fertilizing.

It’s all about the soil. Most soil doesn’t have all the nutrients needed for optimal growth, which means you won’t get the harvest or flower bloom desired.

There are six primary nutrients that plants require—carbon, hydrogen, oxygen, nitrogen, phosphorus, and potassium. The latter three nutrients come from the soil.


N-P-K Fertilizer Labels

Every fertilizer label will give information relating to its “N-P-K” content, expressed as a number ratio. On the label, you’ll see numbers like 5-10-10, 10-10-10, and 10-6-4.

There is valuable information in the labeled numbers: They indicate the amount of nitrogen, phosphorus, and potassium (standardized in that order) in the particular fertilizer blend.

For example, 100-pound bag of 10-10-10 contains ten pounds of each element. The rest is filler, which gives it bulk and makes it easier to spread.

  • Nitrogen (N) is needed for leaf growth and is responsible for making plants greener. Plants that are almost all leaves need a lot of nitrogen, so look for a fertilizer with a high first number. The higher the number, the more nitrogen the fertilizer provides. This is why most lawn fertilizers are high in nitrogen, with formulations like 24-4-12 or 20-2-6.
  • Phosphorus (P) promotes root development, which helps to anchor and strengthen plants. It also increases bloom and fruit production. Tomatoes and root crops favor “snacks” of 5-10-10.
  • Potassium (K), also known as potash, helps the plant fight off diseases and keeps it vigorous, enabling them to withstand extreme temperatures and ward off disease. Plants deficient in potash may display stunted leaves and fruit and be extra sensitive to drought. Because most soils already contain potassium, the third number in the fertilizer ratio tends to be the smallest.

Other Plant Nutrients

When it comes to fertilizers, much attention is paid to nitrogen, phosphorus, and potassium, but there are other key nutrients needed for overall plant health as well, though in smaller quantities.

  • Calcium (Ca), which improves general plant vigor and promotes the growth of young roots and shoots.
  • Magnesium (Mg), which regulates the uptake of nutrients, aids seed formation, and contributes to the dark green color of leaves, which is important for effective photosynthesis.
  • Sulfur (S), which maintains that dark green color, encouraging vigorous plant growth.

Soil test results sometimes come with recommendations to add these trace minerals to the soil if they are found to be deficient.

Read more about organic soil amendments.

How do you know what your soil needs? Knowing your plants’ growing medium is key to knowing what kind of fertilizer(s) will benefit them. You want to add what they lack, not what they do not need.

The very first step in almost any gardening endeavor should be a soil test. For accurate and useful results, go through the folks at your County Extension Office. They will test the soil, explain the results, and provide recommendations for actions to take. Read more about soil testing for a healthier garden.

Because soil continually changes, you should have your soil tested every 2 to 3 years. Keeping records of test results, fertilizer applications, and any other soil amendments you make is always a good idea.

Natural and Organic vs. Synthetic Fertilizers

Fertilizer providing the N-P-K nutrients mentioned above can come in both organic and synthetic versions. What’s the difference?

  • Organic fertilizers come from sources such as manure, blood meal, cottonseed meal, feather meal, crab meal, etc. (Bear in mind: Not all products labeled “natural” are organic. Greensand—derived from inorganic mineral-based or “rock” matter—is an example of a natural, although inorganic, material.) Organic fertilizers work in concert with soil microbes that break fertilizers down for plant uptake. Because they don’t add excess salts and acid to the soil, organic fertilizers are beneficial in encouraging healthy soil biology rich in microbial activity.
  • Synthetic fertilizers are lab-made and derived from compounds like ammonium nitrate, ammonium phosphate, superphosphate, and potassium sulfate. They expedite plant growth and can contribute to bloom rate in flowering plants. However, they are high in salts and can be detrimental to populations of beneficial microorganisms and also leach into water sources. Applying too much synthetic fertilizer can “burn” foliage and damage your plants. Synthetic fertilizers are great for a boost, but do little to improve your soil’s long-term health, texture, or long-term fertility. Because synthetic fertilizers are highly water-soluble, they can also leach out into streams and ponds.

In general, organic fertilizers need time to enrich the soil, so they’re best applied in the fall so the nutrients will be available in the spring. For the spring, some fertilizers combine the best of both worlds with an organically-based fertilizer mix that also contains small amounts of synthetic fertilizers to ensure the immediate availability of nutrients.

Note that the N-P-K ratio of organic fertilizers is typically lower than that of a synthetic fertilizer. By law, the ratio label can only list nutrients that are immediately available.

Granular vs. Soluble Fertilizers

You may also notice that there are both granular and soluble formulations.

  • Granular fertilizers are solids that must be worked into the soil and given time (and water) before they dissolve and become available to plants.
  • Slow-release fertilizers are a subset of granular formulations. A portion of the fertilizer is not immediately available to the plant. Nutrients are metered out over several weeks. Therefore, they are applied less frequently.
  • Sometimes called “liquid feed,” soluble fertilizers are sold as either ready-to-use solutions or packaged dry-milled materials that need to be dissolved in water. These tend to be quick-release fertilizers high in nitrogen that result in fast green growth. (Miracle-Gro is a good example of a soluble fertilizer.)

To build the long-term health and fertility of your soil, we recommend using granular organic fertilizers. Supplementing with an additional water-soluble fertilizer is a way to ensure that your plants have the nutrients they need when they need a boast (during active growth).

Shopping for Fertilizer

Shopping for fertilizer can be confusing because plants have individual nutrient requirements.

  • If you don’t have any specific soil needs, a 5-5-5 fertilizer is an all-purpose fertilizer that provide plants with what they need for healthy growth.
  • Evergreens — holly, rhododendron, yew, and others — not only need high nitrogen to keep them green, but several trace elements as well. Evergreen food may have an analysis of 30-10-10, plus a dose of copper, molybdenum, and iron.
  • Flowering annuals, on the other hand, burst into bloom when nitrogen is held back. The tonic they need is 5-10-10..
  • Good-quality bonemeal worked into the soil around newly planted bulbs keeps them springing up for several years.

Another Kind of Fertilizer: Compost Tea

Before buying bags or bottles of fertilizers, consider how you might add nutrients to the soil by improving its biology. Try compost tea, a liquid produced by extracting beneficial microbes (bacteria, fungi, protozoa, and nematodes) from compost.

Applying compost tea to both soil and plant foliage adds those beneficial microorganisms to the growing medium, which boosts plant health and encourages growth. Compost tea is made using a brewing process similar to that used for making beer. Active compost, a brewing kit, and a little information can go a long way toward turning your landscape into a thriving ecosystem. See information on how to make compost tea.

Now that you understand more about fertilizers, see how to apply fertilizer to your garden!

Fertilizer How To – What Fertilizer Numbers Mean and What to Choose

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  • Fertilizer How To – What Do the Numbers on a Fertilizer Bag Mean? What Fertilizer to Choose?

    How to Choose Fertilizer Based on Fertilizer Numbers?

    Caution: Your choice in fertilizer will depend largely on your objective, geography, climate and circumstance. Choosing the wrong fertilizer or applying fertilizer under the wrong conditions may damage your lawn, garden or plants.

    What Fertilizer to Choose?

    With fertilizer numbers and the soil test in mind, here are HowtoGardenLawn.com‘s fertilizer recommendations, including some common fertilizer numbers :

    New Lawn or After Overseeding: Starter lawn fertilizer high in phosphorus – e.g., 10-18-10 (Scotts Turf Builder Starter Food for New Grass Plus Weed Preventer)
    Mature Lawn: Lawn fertilizer high in nitrogen and low in phosphorus – e.g., 30-0-3 (Scotts Turf Builder Lawn Food) or if you want a dummy-proof, organic fertilizer choose Milorganite (Organic NON-burning fertilizer)

    Fall/Autumn Lawn Fertilizing Before Winter: Lawn fertilizer high in nitrogen, low in phosphorus, and medium in potassium – e.g., 32-0-10 (Scotts Turf Builder Winterguard, 15,000 ft. coverage)
    General Plant Growth: General plant fertilizer – e.g., 4-4-4 (Jobe’s Organics All Purpose Fertilizer with Biozome, 4-4-4 Organic Fast Acting Granular Fertilizer for All Plants, 4 pound bag)
    Super Bloom Plant Growth: Plant bloom booster – e.g., 10-30-20 (J R Peters Inc 51024 Jacks Classic No.1.5 10-30-20 Blossom Booster Fertilizer)
    Tomato or Vegetable Garden: e.g., Miracle-Gro 3002610 Shake ‘N Feed Tomato, Fruits and Vegetables
    Potted Flowers or Flower Garden: e.g., Miracle-Gro 3001910 Shake ‘N Feed All Purpose Continuous Release Plant Food

    For Evergreens or other trees: Try a fertilizer stakes or spikes. e.g., Miracle-Gro Fertilizer Spikes for Evergreens

    How to Fertilize?

    How to apply fertilizer on lawn has been covered in our post: How to Fertilize Lawn? When to Fertilize? DIY Fertilizer FAQ’s

    Clear as mud? Hope the fertilizer infographic and how to choose fertilizer information helped! Let us know if you have any further fertilizing questions.

    • Garden Fundamentals – become a better gardener

      We eat 3 times a day and the food we eat provides all of the nutrients we need to live. The chemicals in food are used by our bodies to grow and maintain our body parts. The protein you eat helps build muscles. Carbohydrates provide energy that is used for all kinds of things such as moving, breathing, thinking and eating more food.

      Most of the food we eat is in the form of large molecules such as protein, carbohydrates, DNA, and fats. Our digestive system takes these large molecules and breaks them down into smaller molecules like simple sugars and nitrates. Our bodies then use these small molecules as building blocks to build new large molecules. Our bodies are actually a very efficient recycling plant. We take food in, break it down into basic building blocks, and then use these building blocks to create complex body parts.

      Plants differ from humans and other animals in that they do not have a digestive system. Therefore, they are not able to break down large molecules. Plants must start with small molecules like nitrate and phosphate and build the large molecules they need.

      Fertilizer – select the right NPK, by Robert Pavlis

      Plants Use Fertilizer to Build Large Molecules

      Plants take small molecules such as carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium and dozens of other minor nutrients, and use them to build large molecules such as sugars, carbohydrates, oils, protein, and DNA. These large molecules are used for everything that happens in the plant. Carbohydrates are used to build cell walls, which in trees, eventually turn into wood. Enzymes are proteins that make all of the chemical reactions in a plant work. Sugars and carbohydrates are the energy source that allows the plant to grow. The production of flowers and fruit require many different types of large molecules and all of these are made by the plant using the small molecules we call nutrients.

      The figure below shows a list of some of the large molecules found in plants along with the nutrients used to make the molecules. All of the molecules contain carbon, hydrogen and oxygen. Nitrogen and phosphorus are also common. Other nutrients are used less often, and in smaller amounts, but they are critical for building the large molecules.

      Nutrients required by plants to build large molecules

      If a single nutrient is missing the plant will not be able to produce all of the large molecules it needs, and plant growth will slow down or even stop. A gardener’s job is to make sure that plants always have access to the nutrients they need. That seems like a daunting task, but it is easier than you think. There are two important concepts to understand:

      • Plants need much more than just the nitrogen, phosphorous and potassium found on fertilizer labels.
      • They need to eat all of the time—not just once or twice a year when you fertilize.

      What is NPK?

      It is time to feed your plants and you go to the store to pick up some plant food which is called fertilizer. Most packages of fertilizer show the letters NPK followed by some numbers, for example: NPK 10-5-5. NPK stands for nitrogen, phosphorous and potassium which are three of the most important nutrients required by plants. The numbers following NPK are the percent amounts of each nutrient. An NPK value of 10-5-5 means that the fertilizer contains 10% nitrogen, 5% phosphorus and 5% potassium.

      NPK is the common way to describe fertilizer in North America but some countries use an NPKS value where the S stands for the amount of sulphur. Sulphur can be as important as the other three nutrients.

      For my techi readers: The above statement “10-5-5 means that the fertilizer contains 10% nitrogen, 5% phosphorus and 5% potassium” is not totally correct. For a detailed explanation see my Garden Myths blog post called Fertilizer NPK Ratios – What Do They Really Mean?

      The letters N, P and K are the symbols used by chemists as a short hand to describe the elements. N is used for nitrogen and P for phosphorus. The letter K is used for potassium and stands for kalium, the original Latin name for potassium. If you have trouble remembering whether P is for phosphorus or potassium, remember that the three nutrients are listed in alphabetical order. Phosphorus comes before potassium alphabetically and so the last letter in the list, K, is short for potassium.

      A bag of plant food that contains 10% nitrogen, 5% phosphorus and 5% potassium, also has 80% of some other material, but you can ignore it since it has no effect on your plants. If the fertilizer is in a dry form like lawn fertilizer the 80% may be small stones or other dry inert material. If the fertilizer is in liquid form the extra material is water.

      The History of NPK Ratios

      To understand fertilizer it is worth while looking at the history of the NPK ratios. How did they develop? Who decided that a formula of 10-5-5 was the right formula? Is it the right formula for every plant?

      Quite a few years ago a company providing fertilizer decided to market the concept of a balanced fertilizer and decided, arbitrarily, that a 10-10-10 formula would work well. This was a marketing tactic that was not based on any kind of science. Customers bought into the idea and so you now see a lot of references using the term balanced fertilizer and recommending a 10-10-10 formulation. On the surface it seems to make sense. Plants need nitrogen, phosphorus and potassium so why not give it to them in equal amounts.

      To be competitive, other companies decided that they would start promoting a fertilizer that was based on the actual nutrients required by plants. Scientists took various plants and analyzed their content. For example, lawn grass is high in nitrogen relative to P and K, and the company developed an 18-10-10 fertilizer for grass. A new marketing approach was born. Make fertilizer specific to the needs of the plant.

      Over time, more research showed that plants used a lot of phosphorous to make blooms and roots, and so manufacturers developed bloom boosters and starter fertilizers with formulas like 10-52-10. This idea also seemed to make sense. Give plants the fertilizer they need, at the time they need it. Starter fertilizer is used when transplanting a new plant so that new roots grow quickly. Once established, a plant could be given a fertilizer higher in nitrogen since the plant is now focused on growing new leaves. At bloom time go back to a 10-52-10 to give it another phosphorous boost.

      Start Fertilizers and Bloom Boosters are a myth – they don’t work. For more details on this see Bloom Booster – Nonsense #5 on my GardenMyths.com blog.

      These advances in fertilizer development resulted in an avalanche of different fertilizer formulations and gardening experts were eager to buy into the idea. They started recommending the right fertilizer for each type of plant and for various times of year. These recommendations are still popular in today’s books and websites, and they are extremely confusing.

      Don’t worry – I will make fertilizer simple for you in this and the next couple of posts.

      How Does a 10-10-10 Fertilizer Compare to a 5-5-5 Fertilizer?

      This is a very common question. Should I use a 10-10-10 fertilizer or a 5-5-5? What is the difference? The answer is simple. It doesn’t matter which you use because they provide the same relative amount of nutrients. It is however important that you use the correct amount of fertilizer.

      When dealing with fertilizer there are two things that are important: the actual amount (the weight) and the ratio of nutrients.

      The ratio is the relative amount of each nutrient. In the two examples above, there is an equal amount of each nutrient and so the ratio is 1:1:1 for both of them. In comparison, an NPK value of 20-10-10 has twice as much nitrogen as phosphorus or potassium and so the ratio is 2:1:1.

      A 10-10-10 fertilizer has 10% of each nutrient and a 5-5-5 has 5% of each nutrient so a bag of 10-10-10 contains twice as much fertilizer as the same sized bag of 5-5-5. The 10-10-10 is more concentrated, but both have the same ratio.

      Which one is best for your garden? It doesn’t matter since they have the same ratio. If you need to add equal amounts of N, P and K, either one works just as well. However, you will have to use twice as much of the 5-5-5 to provide the same level of nutrients as the 10-10-10.

      The most important thing when buying fertilizer is to buy the correct ratio so that you get the correct relative amounts of nutrients. In general, a fertilizer with higher numbers is cheaper. Many of the liquid fertilizers on the market are very dilute, in the range of 1-1-1, and they are also some of the most expensive fertilizers you can buy. From a price point of view, always buy the one with the higher numbers, provided it has the correct ratio.

      What is the Correct NPK Ratio For My Plant?

      Fertilizer is now available in many different NPK ratios and knowing which one to use can be very confusing. As you begin to understand fertilizers and plants you will start to realize that the answer is actually very simple. It is however very instructive to look at the question in more detail.

      A million web sites and thousands of books give you recommendations for fertilizer. Lawns need one formula, tomatoes need a different one. Tress and perennials are different again. It all gets very confusing and it is all bad advice.

      Statements such as the following are always wrong:

      • Use 5-10-5 fertilizer for tulips.
      • Use 34-10-10 on grass in spring and a 15-5-5 in fall.
      • Use 5-7-3 for vegetables.

      Let me repeat the last statement—the above advice is always wrong. The advice is wrong for several reasons.

      Tulips might in fact need more phosphorus—the middle number—but it is just as likely that this advice is based on old myths and not on actual science. At best these recommendations are based on plant tissue analysis and not on nutrient levels in your soil.

      The main reason the above recommendations are wrong is because you don’t add fertilizer to plants – you add it to soil. Read on and this will make sense shortly.

      You Don’t Add Fertilizer to Plants

      The idea that we feed the plant what they need seems to make perfect sense but it ignores one very important point. Plants get their food from the soil. You don’t add fertilizer to plants—you add it to soil. This is an extremely important concept that is not well understood and is best explained by a simple example. Assume that your soil is naturally very high in phosphorous. The fertilizer you use at transplant time, or for tulips, or to get more blooms does not need a high amount of phosphorous because your soil already has more than your plants can use. The fertilizer you add to the garden should be a supplement to what is lacking in your soil.

      If your soil has high phosphorus levels, any fertilizer you add – for any type of plant – should contain no phosphorus because you already have too much.

      Plants absorb the nutrients they need from the soil. If grass needs more nitrogen, it takes more nitrogen from the soil than a plant that needs less nitrogen. If a plant is ready to make flowers and it needs more phosphorus, it takes more phosphorus from the soil.

      Matching fertilizer to what a plant needs does not make sense. Instead you should match the fertilizer to what the soil needs. If your soil is low in nitrogen and high in phosphorus you should use something like a 20-0-5 fertilizer for all of your plants no matter what type they are.

      The author that recommends a 5-10-5 fertilizer for tulips has no knowledge about your soil. So they can’t make correct fertilizer recommendations for your soil.

      Consider this example. For years the common lawn fertilizer recommended for North America has been some thing like 34-10-10, high nitrogen and fairly high P and K. Over the years we learned to understand two facts. First, most urban garden soil in North America has lots of phosphorus – it does not need any more to grow grass. Secondly, the excess phosphorus ends up polluting rivers and lakes. So now many states have banned phosphorus in lawn fertilizer. In Ontario, I noticed 2-3 years ago, that many brands have now eliminated P from lawn fertilizer.

      But people still recommend adding extra phosphorus for their bulbs! That is dumb. If our soil has lots of phosphorus for grass, then it also has lots of phosphorus for bulbs. I grow over 200 different kinds of spring bulbs and I have never added phosphorus – they grow and flower just fine.

      In my next post I’ll have a closer look at specific plant nutrients.

      If you like this post, please share …….

      Fertilizer Numbers – What Is NPK

      Standing in the fertilizer aisle of a garden or farm store, you are faced with a dizzying array of fertilizer options, many with a series of three numbers like 10-10-10, 20-20-20, 10-8-10 or many other combinations of numbers. You may be asking yourself, “What do the numbers on fertilizer mean?” These are NPK values, which leads to the next question of, “What is NPK?” Keep reading to learn more about fertilizer numbers and NPK.

      What Do the Numbers on Fertilizer Mean?

      The three numbers on fertilizer represents the value of the three macro-nutrients used by plants. These macro-nutrients are nitrogen (N), phosphorus (P) and potassium (K) or NPK for short.

      The higher the number, the more concentrated the nutrient is in the fertilizer. For example, numbers on fertilizer listed as 20-5-5 has four times more nitrogen in it than phosphorus and potassium. A 20-20-20 fertilizer has twice as much concentration of all three nutrients than 10-10-10.

      The fertilizer numbers can be used to calculate how much of a fertilizer needs to be applied to equal 1 pound of the nutrient you are trying to add to the soil. So if the numbers on the fertilizer are 10-10-10, you can divide 100 by 10 and this will tell you that you need 10 pounds of the fertilizer to add 1 pound of the nutrient to the soil. If the fertilizer numbers were 20-20-20, you divide 100 by 20 and you know that it will take 5 pounds of the fertilizer to add 1 pound of the nutrient to the soil.

      A fertilizer that contains only one macro-nutrient will have “0” in the other values. For example, if a fertilizer is 10-0-0, then it only contains nitrogen.

      These fertilizer numbers, also called NPK values, should appear on any fertilizer you purchase, whether it is an organic fertilizer or a chemical fertilizer.

      What is NPK and Why is it Important?

      So now that you know what the numbers on fertilizer mean, you need to know why NPK is important to your plants. All plants need nitrogen, phosphorus and potassium to grow. Without enough of any one of these nutrients, a plant will fail.

      Nitrogen (N) – nitrogen is largely responsible for the growth of leaves on the plant.

      Phosphorus (P) – Phosphorus is largely responsible for root growth and flower and fruit development.

      Potassium (K) – Potassium is a nutrient that helps the overall functions of the plant perform correctly.

      Knowing the NPK values of a fertilizer can help you select one that is appropriate for the type of plant you are growing. For example, if you are growing leafy vegetables, you may want to apply a fertilizer that has a higher nitrogen number to encourage leafy growth. If you are growing flowers, you may want to apply a fertilizer that has a higher phosphorus number to encourage more blooms.

      Before you apply fertilizer to your garden beds, you should have your soil tested. This will also help you determine what balance of fertilizer numbers will be appropriate for your garden’s soil needs and deficiencies.

      Whether you’re trying to green up your lawn or raise award-winning pumpkins, you need to feed your plants. But all those numbers and letters on a bag of fertilizer are confusing. And unless you have a crystal ball, you have no idea what nutrients are already in your soil—or not. Here’s how to take the mystery out of fertilizing to avoid wasting time and money.

      What do the numbers and letters mean?

      If you (vaguely!) remember the periodic table from high school chemistry, you know that N stands for Nitrogen, P for Phosphorus, and K for potassium. These nutrients are the three numbers on a fertilizer bag listed in order (N-P-K). So, a fertilizer that contains 5-10-10 means it has 5 percent nitrogen, 10 percent phosphorus (phosphate), and 10 percent potassium (potash). A “complete” fertilizer contains all three.

      What do the different nutrients do?

      Each nutrient plays a different role. Nitrogen boosts green leafy growth. “It’s like the gas pedal,” says John Esslinger, horticulture educator at Penn State Extension. “That’s why many lawn fertilizers are high in nitrogen to promote leafy growth.” Phosphorus helps strong roots form, so plants lacking in phosphorus may be purple-ish and slow-growing. Potassium helps promote vigorous growth and hardiness, so a deficit may result in wimpy fruit or spindly plants that fall prey to pests and diseases.

      How do I pick a formula?

      Now you’ve got some homework to do. “Before you add anything to your lawn or garden, get a soil test,” says Esslinger. “Otherwise, you have no idea where you’re starting from and what your soil needs or doesn’t need.” In fact, some nutrients, such as phosphorus, are good at staying in the soil; you may not need to add them every time you fertilize. And more is not better. It’s not only a waste of money to add stuff you don’t need—it’s also bad for the plants. For example, too much nitrogen will grow monster tomato plants, but you may not get any fruit. And really, then, what’s the point?

      Get your soil test kit from a local garden center or your area’s coop extension service; they’re typically about $10 to $20, and you only need to do one every few years. The master gardener at the county extension service can help you decipher the results and explain how much of each nutrient you need to apply. A balanced fertilizer (with all the same numbers, such as 5-5-5) may be okay for many situations such as flower and vegetable gardens, but only a soil test will tell for sure.

      Finally, your test also will include your soil’s pH, a measure of how acidic or alkaline your soil is. It’s another important aspect of soil fertility because if your pH is too high or too low, your plants may not be able to use the nutrients you apply, says Esslinger. Based on your test results, an application of lime to raise pH or sulfur to lower pH may be recommended.

      Best Tools for Healthy Soil

      Luster Leaf Soil Tester Luster Leaf amazon.com $6.59

      DIY a quick soil analysis.

      Laboratory Soil-Test Kit Whitetail Institute amazon.com $14.99

      Get complete results in one week.

      Sonkir Soil pH Meter Sonkir amazon.com $10.99

      Get instant reads on soil pH.

      Fiskars Big Grip Trowel Fiskars amazon.com $9.33

      Deep trowel to add fertilizer with ease.

      Arricca Elin Sansone Arricca SanSone has written about health and lifestyle topics for Prevention, Country Living, Woman’s Day, and more.

      Fertilizers come in such a huge variety of mixtures and different ingredients that it can be hard to narrow down which one you need. 10-10-10 is a common and popular formula you’ve probably seen on store shelves a million times, but what is it and what is it good for?

      The numbers 10-10-10 represent the amounts of nitrogen, phosphorus, and potassium – or as they are commonly known, NPK – in the formula. That means there’s 10% of each one of these elements. NPK are considered the primary nutrients that every plant needs to survive.

      10-10-10 is considered an all-purpose, balanced fertilizer that you can use for all kinds of plants and situations. In this article, we’ll discuss what it is, when to use it, and why you might want to put it back on the shelf.

      What is 10-10-10 Fertilizer?

      10-10-10 fertilizer is considered a complete fertilizer because it mainly consists of the primary nutrients. Some formulas will have added iron or calcium to target certain plants.

      There is no one definition of what 10-10-10 fertilizer is because each company may have different ingredients. They all contain 10% of each element, but other than that, they can vary. The more common ingredients are ammonium hydroxide, urea, ammonium nitrate, phosphoric acid, and potassium hydroxide.

      These ingredients are made to dissolve quickly so they’re readily available to plants. This also means that they may be lost due to erosion or decay. When you look at application rates for this fertilizer, they usually recommend frequent applications because it can disappear so quickly.

      10-10-10 is considered an inorganic or synthetic fertilizer. That means it is man-made with minerals or synthetic chemicals.

      Advantages of 10-10-10 Fertilizer

      The biggest advantage is that it’s easy to use. You don’t have to think about what nutrients your plants need. You just sprinkle the 10-10-10 around them. It’s also readily available to plants and breaks down quickly.

      Disadvantages of 10-10-10 Fertilizer

      Advertisers will tell you that you can’t go wrong with an all-purpose fertilizer, but they aren’t all they’re cracked up to be.

      One disadvantage of any inorganic fertilizer is they may crust on top of the soil rather than soaking deep into the roots. Also, they don’t enrich the soil long-term, but provide a quick fix of nutrients. Here are some other issues associated with 10-10-10 fertilizer.

      Excessive Nutrients

      When using this type of fertilizer, you run the risk of giving your plants excessive amounts of nitrogen. This may increase leaf production but diminish fruiting. You’ll often see this with tomatoes. Too much nitrogen can also encourage fast, spindly growth, causing the plant to be vulnerable to disease.

      You also run the risk of adding excess phosphorus, which can increase your risk of chlorosis. Phosphorus can also kill the symbiotic mycorrhizal-forming fungi that live in the soil. When microorganisms in the soil die, it causes an inability for the plant to absorb iron and other micronutrients. It can shut down the plant’s production of phytochelatins. These organic molecules help regulate iron intake and other important nutrients.

      Adding nutrients when they’re not needed can cause deficiencies, and an imbalance in nutrients and the plant’s ability to absorb them.

      Dangerous Chemicals

      Natural fertilizers don’t contain caustic chemicals, but 10-10-10 fertilizers do – as you can tell from the warning labels on the bag. Some of the chemicals used in complete fertilizers are harmful to our health. When you’re applying fertilizer, protective clothing is recommended. They also shouldn’t be used around children.

      They may also contain heavy toxic metals that can damage our health. I’m sure you have seen the lawn signs that say “stay of the grass” because dangerous chemicals have been applied there. Personally, I choose not to place things that are corrosive and can harm my family, pets, and lawn equipment where I am growing my food.

      Nitrogen Runoff

      10-10-10 fertilizer contains a lot of nitrogen – 10%, of course. This nitrogen can erode during spring rains and pollute your streams and ponds. On many bags of fertilizer, you’ll see a warning that states it’s toxic to fish and invertebrates. That can mean that you’re killing your earthworms and other microbial life. For any organic farmer, that’s counterproductive.

      I live in Kentucky and agricultural runoff from my state pollutes the Gulf of Mexico. Our excess nitrates travel via waterways down to the Ohio River to the Mississippi River and into the Gulf of Mexico.

      In the gulf, excessive nitrogen causes algae blooms. This has had a detrimental impact on the fishing and crabbing industries in the Gulf shore states.


      Inorganic formulas also contain a lot of salt as part of their chemical makeup. These salts can build up in your soil. Fertilizer salts aren’t the same as the ones we sprinkle on our French fries.

      Salts found in complete fertilizer mixes are basically an inorganic mineral that can be dissolved in water. Some examples are ammonium nitrate, calcium chloride, and potassium sulfate.

      What’s the problem with these salts? After all, some of them are mined from the earth. Proponents of inorganic fertilizers will tell you that this makes them natural.

      What actually happens is that the plant doesn’t need an abundance of salts. When the salt isn’t absorbed by the plant, it sits in the soil. This salt builds up in the soil and can eventually clog the roots of your plants. During dry weather, the salts don’t leach away and can burn or damage roots and plant stems. The result? You end up with a dead plant.


      In contrast to synthetic fertilizers, organic fertilizers come from natural sources such as manure, compost, blood meal, green sand or bone meal.

      The downside is that organic fertilizers have lower concentrations of nutrients. However, they build up the soil and provide nutrients for microorganisms. These soil microbes work in tangent with your plants, helping them absorb nutrients and fight disease.

      It’s interesting that to be labeled a fertilizer, government regulations only look at N, P, and K levels. Holistic gardeners realize that there are actually about 70 nutrients that plants need to be healthy.

      This means that several materials we think of as organic fertilizers are labeled as supplements instead. Compost and kelp are two examples, even though both of these can improve the health of your soil and plants.

      Instead of 10-10-10 fertilizer, consider using one or a mix of the following:

      • Bone meal
      • Cottonseed meal
      • Alfalfa pellets
      • Bat guano
      • Fish emulsion
      • Composted manure

      Use this handy Fertilizer Calculator to figure out how much of each material you need.

      If you don’t want to go to the trouble of figuring out an alternative, you can find good 5-5-5 fertilizers that are all-natural and organic. Just double up on your dose.

      Soil Testing

      First of all, before you make ANY fertilizer decisions you should know what you are dealing with. Take a soil test. Having a complete soil test will tell you what your soil does and doesn’t have.

      Maybe for the past two years, you have been spreading wood ashes in your garden. When you do your soil test, you learn that you have a high level of potash, which ashes are rich in. This year, maybe you want to cut back.

      That same test tells you that you are low in phosphorus. A 10-10-10 fertilizer isn’t going to meet your needs because it will give you too much nitrogen and potassium. A fertilizer higher in phosphorus such as bat guano may be up your alley.

      Choosing Fertilizers Based On Plant Needs

      Different plants have different needs, and to complicate that a bit, plants have varying needs during the growing season.

      For example, let’s look at tomato plants. When they’re young, a dose of nitrogen or a “complete” fertilizer may be a good thing because the plants are growing and making leaves.

      When the tomato starts to set fruit, it needs less nitrogen and more phosphorus. Now, a 10-10-10 fertilizer is inappropriate. At that point, tomatoes need calcium and magnesium to support fruit development. These vital secondary nutrients are not commonly found in an all-purpose fertilizer mix.

      Carrots are another good example. They need a higher level of potash and a lower level of nitrogen than most crops, so a 10-10-10 fertilizer won’t meet all its needs. Studies have shown that carrots love a dose of kelp and benefit from its micronutrients.

      These examples aren’t to make gardening seem hard or complicated. Just be aware of some of the differences in how your plants grow so you can provide them with what they need. Of course, your crops will probably be fine with an all-purpose fertilizer, but be aware that it’s not always the right solution.

      Ornamentals, Trees and 10-10-10 Fertilizer

      You’ll often hear that perennials such as fruit trees, berry bushes, and ornamental specimens should receive a dose of 10-10-10 fertilizer in the early spring. Even in established soils, the logic is that they can always use a boost.

      However, keep in mind that before you start tossing on the fertilizer, you need to consider what you did in fall. Did you spread compost around your trees and add a bunch of mulch? If you did, it will be feeding the soil slowly once the weather warms up, so you may not need a dose of fertilizer.

      Keep Safety in Mind

      If you choose to use chemical fertilizers, take precautions to protect yourself. Dress in long pants and long sleeves and wear protective gloves, eye protection, and a breathing mask.

      Don’t let your pets or kids walk on fertilized plants, and be sure to follow the manufacturer’s directions to the letter.

      The Bottom Line on 10-10-10 Fertilizer

      I hope that what you take away from this article is that you should carefully consider what type of fertilizers you apply to your garden.

      It’s probably clear to you that I am an advocate for organic agriculture. I want to live a lifestyle that is supportive and healthy for the environment. I want my farm, my animals and my family to benefit from good health.

      In doing so, I consider the needs of my garden plants and look at the short and long term solutions to building healthy soil. 10-10-10 fertilizer has its place, but it isn’t the catch-all that it is painted as. Use it wisely and know when to reach for something else.

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      How to fertilize trees, shrubs, flowers and fruits

      Lawn fertilizing is comparatively easy, as you measure the lawn area and apply at the rate on the label. But fertilizing trees, shrubs, vines, fruits, perennials and annuals is often less clear-cut. Let’s examine the guidelines for non-lawn plants.

      • Plants need nutrition like humans need food, and the three elements required in greatest quantity are nitrogen, phosphorus and potassium, which are the three primary numbers listed on every fertilizer label.

      • Lawn fertilizers are high in nitrogen, the first number in an analysis like 30-5-5, to promote green, leafy growth.

      • Trees, shrubs, perennial flowers, annual flowers, fruits and vegetables require a more “well-balanced” or “complete” fertilizer, in which the three main nutrients are closer in proportion, such as 10-10-10, which provides nitrogen for green, healthy foliage and phosphorus and potassium for flowering, fruiting and root development.

      • Although many fertilizers are specially packaged for plants like roses, tomatoes or trees, an all-purpose, well-balanced fertilizer like 10-10-10 is effective, eliminating the need for many individual types.

      • Dry granular fertilizers or water-soluble Miracle-Gro types are both beneficial.

      • Soils in the Upper Midwest are generally considered fertile. Adding fertilizer can boost growth and production, helping plants reach their maximum.

      • Fertilizer isn’t medicine for sick plants. Force-feeding a declining plant can make matters worse. Fertilizer turns an OK plant into a more prolific plant.

      • For best results, soil testing of gardens and yards can provide a baseline to determine present fertility and recommend additions. North Dakota State University and the University of Minnesota both have soil-testing labs.

      • Don’t fertilize during dry periods. Plants can’t use fertilizer without adequate moisture. Fertilize before a rain, or water after application.

      • Organic fertilizers are derived from plant or animal sources. Manure, compost and other organics are usually lower in fertilizer analysis with nutrients released slower but are longer-lasting, plus they enrich soil tilth.

      • Inorganic or chemical fertilizers are derived from minerals or manufactured products. They react faster than most organics and are higher in analysis, but dissipate quicker and they generally don’t improve soil tilth.

      • Both organic material and inorganic fertilizer can be combined effectively, if desired.

      • Apply fertilizer to trees, shrubs, fruits and perennials when spring’s flush of rapid growth begins, and then monthly through June.

      • July 4 is the cutoff date for fertilizing trees, shrubs, fruits and perennial flowers. Fertilizing later stimulates growth that might not have sufficient time to toughen or harden off before winter.

      • Fertilizer is especially effective on younger trees, shrubs, fruits and perennials. Older, large, established plants usually grow fine without fertilizer additions.

      • Starter fertilizers help vegetable and flower transplants establish quicker.

      • If in doubt about quantity, always err on the low side, as too much can burn plants. Follow the label.

      • Granular fertilizer is best cultivated shallowly into the soil surface after application and watered in.

      • Fertilizer spikes provide nutrition, but materials don’t move laterally a great distance, limiting spikes’ efficiency.

      • For vegetable gardens, fertilizer can be broadcast and tilled in before planting, or side-dressed in bands beside rows or in a circle around individuals. Follow label directions, which for 10-10-10 is about 2 cups (1 pound) per 100 square feet or about a half cup per 10 running feet of row.

      • For trees, apply 1 cup of 10-10-10 for every inch of trunk diameter (measured 4½ feet above ground level) and distribute evenly around the root zone inside and outside of the canopy’s dripline, not next to the trunk.

      • For shrubs, spread 1 cup of 10-10-10 evenly around large, 5- to 6-foot-high established shrubs. Apply a half cup to small and less-established shrubs.

      • For perennial flowers, rhubarb and asparagus, spread 1 cup of 10-10-10 per 100 square feet of bed, or band each plant with a fourth to a half cup. Cultivate in and water.

      • For strawberry patches, follow vegetable garden guidelines.

      Landscaping Lowdown: Understanding the Different Types of Fertilizer

      Photo: istockphoto.com

      Your lawn and garden need a variety of nutrients to grow and stay healthy. Soil is an important source of key nutrients like nitrogen (N), phosphorus (P), and potassium (K), but it doesn’t always contain them in adequate amounts. That’s why many homeowners rely on commercial fertilizers as a supplement. Fertilizers come in an extensive variety of types and nutritional profiles, each of which impacts your plants—and the environment—in a unique way. Read on to acquaint yourself with the types of fertilizers available on the market today, so you can shop your garden center for the right solution with confidence.


      Fertilizer supplies plants with three primary nutrients: nitrogen, phosphorus, and potassium. This nutrient trifecta is so important to the health of plants that all fertilizers display an NPK value on their packaging. The NPK value represents the percentage by volume of nitrogen (N), phosphorus (P), and potassium (K) that a fertilizer contains. For example, a fertilizer with an NPK value of 16-16-16 contains 16 percent nitrogen, 16 percent phosphorus, and 16 percent potassium (the remainder of the fertilizer comprises filler ingredients). It also means that the fertilizer has an NPK ratio of 1:1:1; that is, it contains equal amounts of the three main nutrients. Similarly, types of fertilizer with the NPK value of 24-8-16 contain 24 percent nitrogen, 8 percent phosphorus, and 16 percent potassium—that’s an NPK ratio of 3:1:2.

      Before choosing a fertilizer, determine the optimal NPK ratio for your soil by determining the existing nitrogen, phosphorus, and potassium levels using a soil nutrition testing kit (available for $8 to $25 at home centers, nurseries, and online). If the soil test reveals that all three nutrients are present in a roughly equal amount, opt for an all-purpose fertilizer with an NPK ratio of 1:1:1. These fertilizers contain a balanced nutritional profile that is suitable for flowers, vegetables, shrubs, trees, and lawns. A minimum NPK value of 3-3-3 is recommended, but fertilizers in the 1:1:1 ratio come in various NPK values; some popular options include 5-5-5 and 10-10-10. The difference between these two fertilizers is that the nutrients are twice as concentrated in the 10-10-10 option, which means you can apply half as much of it to supply your soil with the same level of nutrients.

      If, on the other hand, the soil test indicates that your soil contains too little or too much of one or more of the three key nutrients, opt for a specialized fertilizer that contains a specialized ratio. For example, if your soil is nitrogen-poor but richer in phosphorus and potassium, you could choose a fertilizer with an NPK ratio of 3-1-2 (such as a fertilizer with an NPK value of 24-8-16). Alternately, you could select a fertilizer with no phosphorus or potassium (with an NPK value such as 10-0-0 or 21-0-0). Specialized fertilizers are also recommended when a plant demands a higher or lower amount of one of the three nutrients. Sweet corn, for instance, thrives in soil with high nitrogen and phosphorus content, which is why fertilizers with an NPK ratio of 2:2:1 are commonly used in sweet corn soil beds.

      Photo: istockphoto.com


      With the proper NPK ratio for your soil in mind, you’ll seek out that set of numbers in one of the two main types of fertilizers on the market: organic and synthetic.

      Organic Fertilizers
      Plant, animal, or mineral remains that are packaged and sold either in their raw state or as pellets are called organic fertilizers. These environmentally-friendly fertilizers typically contain naturally occurring and therefore lower concentrations of individual nutrients than synthetic fertilizers. Home gardeners may pick them for this reason in order to help keep the fertilizer from building up in soil and either burning (i.e. killing) plants or contaminating local water sources via runoff.

      Organic fertilizers—which include cottonseed meal, fish emulsion, bone meal, and blood meal—contribute beneficial microorganisms to soil that will assist in improving its structure over time, which makes it better able to hold water and nutrients. Organic fertilizers also water-insoluble, meaning they won’t dissolve with irrigation. One downside, however, is that organic fertilizer takes significantly longer to improve your plants than liquid or quick-release synthetic fertilizer does. Once spread over the soil surface, organic fertilizers must be organically decomposed by bacteria before releasing nutrients to the soil. Depending on the specific brand and mixture, most organic fertilizers supply nutrients for between three months and 10 years—so even though these fertilizers cost more than the average synthetic fertilizer (typically running anywhere from $.75 to $3 per pound), they generally require less frequent reapplication. Organic fertilizers work well for both garden or lawn applications.

      Synthetic Fertilizers
      Synthetic fertilizers are formulated with chemically processed compounds such as ammonium nitrate or urea. These fertilizers provide a robust source of primary nutrients but don’t contribute any microorganisms to soil, and therefore the soil’s structure and water retention remains the same. Compared with organic fertilizers, synthetic fertilizers are more affordable (around $.50 to $2 per pound) and improve plants more quickly. The flip side to that fast action, however, is that they won’t supply nutrients to the soil for as long—usually only two to eight weeks, depending on the fertilizer – while organic fertilizers provide nutrients for as long as it takes the microorganisms to decompose them. While these types of fertilizers require more frequent application, over-application can lead to fertilizer burn, run-off into local water sources, and even the destruction of existing microorganisms in the soil. If you choose a synthetic option, always carefully follow manufacturer’s recommended amount and instructions.

      • Liquid fertilizers, including both liquid concentrates like Miracle-Gro Liquid All Purpose Plant Food Concentrate and dry powders like Jacks Water-Soluble Fertilizer, are water-soluble fertilizers that should be diluted in water and then applied to soil with a hose-end sprayer or watering pot. These fertilizers rapidly release their nutrients to soil, and they often improve plants within a few days of application. However, since they supply nutrients to soil for only two to three weeks, liquid fertilizers require frequent re-application. These types of fertilizers are most often used when growing outdoor plants and houseplants.

      Photo: istockphoto.com

      • Quick-release granular fertilizers, such as Jobe’s Synthetic All-Purpose Fertilizer, are comprised of small, solid, water-soluble granules. Gardeners must sprinkle or spread the granules over the soil surface, mix them into the topsoil, and water them in order for the fertilizer to decompose and release nutrients into the soil. These fertilizers supply nutrients for three to four weeks, so they require less frequent reapplication than liquid fertilizers. However, quick-release granular fertilizers can take slightly longer—usually a week—to improve plants, due to their slower decomposition rates. These fertilizers are commonly used for both lawn and garden applications.

      • Slow- and controlled-release granular fertilizers are made of water-insoluble granules that are either uncoated or coated with a semi-permeable material. These fertilizers are spread on the soil surface, then covered with soil or compost. The fertilizers decompose and release their nutrients into the soil more gradually than liquid or quick-release granular varieties, supplying nutrients to the soil for anywhere from two to nine months and improving plants in as little as two weeks after application. The slow release diminishes the risk of burning the plant. Controlled-release fertilizers tend to release nutrients at a predictable rate that depends on soil temperature, while the rate of nutrient release in slow-release fertilizers depends on a number of factors including soil temperature, moisture, and pH. Although slow-release granular fertilizers (such as Osmocote Smart-Release Plant Food) are slightly more expensive than quick-release fertilizers, their staying power in soil saves you fertilizer (and money) over time. In fact, gardeners can get away with applying the fertilizer only once or twice per growing season. These fertilizers are commonly used in the lawn and garden.

      • Fertilizer spikes (like Jobe’s Fertilizer Spikes) allow gardeners to avoid the hassles of storing fertilizer bags and spreading fertilizer. The user merely has to drive the solid, water-insoluble sticks into moist soil, where they decompose and release their nutrients. Although fertilizer spikes supply nutrients to the soil for one to three months, they only work on small soil sections. This makes them a better source of nutrients for small trees, plants, and shrubs than for large trees or lawns. Thanks to the tendency of plant spikes to create high concentrations of nutrients in a limited area, they can also contribute to unequal root growth or the dreaded fertilizer burn. To prevent this issue, leave at least three feet between spikes to prevent too much fertilizer from building up in any one area of soil. If the spikes are properly planted, you can expect plants to improve in as little as one week.

      Pro-Booster 10-0-0


      Total Nitrogen (N)……………….10.0% 3.5% Water Soluble Nitrogen 6.5% Water Insoluble Nitrogen

      Nitrogen is a major component of life. The hormones, enzymes and chlorophyll in growing plants are all composed with nitrogen. Protoplasm, the living substance of plant cells, is comprised of 40 to 50 percent nitrogen (on a dry matter basis).

      Plants require more nitrogen than any other soil-born nutrient. Unfortunately, unlike many other plant nutrients, nitrogen does not exist as a natural mineral in soil. Organic nitrogen from plant and animal wastes must be mineralized by soil microbes into nitrate (NO3) to be used by plants. The only known deposit of natural mineral nitrate on earth is in the Atacama Desert located in Northern Chile. It is mined for agricultural and horticultural use and is commonly known as Chilean Nitrate or Natural Nitrate of Soda.

      Pro-Booster 10-0-0 is a combination of vegetable protein meals (such as alfalfa meal, cocoa meal, cotton seed meal, kelp meal, peanut meal, and soybean meal), animal protein meals (such as blood meal, crab meal, dried whey, feather meal, and fish meal), and natural nitrate of soda that contains 10 percent total nitrogen. Pro-Booster 10-0-0 is a fast acting fertilizer with one third of its nitrogen immediately available (water-soluble). The organic nitrogen in animal and vegetable protein meals is 90-95 percent water insoluble and complements the Pro-Booster 10-0-0 mix with its slow release attributes. Pro-Booster 10-0-0 can be side or topdressed wherever extra nitrogen is needed.

      Note: We suggest that you carefully consider your nitrogen needs. Over applying ANY kind of nitrogen can cause more harm than good.

      For Turf
      Pro-Booster 10-0-0 is an excellent spring or summer topdress for soils that predominately need nitrogen. With 3.5 percent soluble and 6.5 percent slow release nitrogen, Pro-Booster 10-0-0 can green-up quickly and provide a longer lasting source of N than conventional fertilizers. Use 10#/1000 ft2 on lawns. Split apply (2 applications of 5# each, 30 days apart) on sandy or well drained soils. Applications during hot, dry periods are not recommended unless irrigation can be provided after applying. Pro-Booster 10-0-0 is dust free and spreads easily through any type of rotary or drop spreader. It is especially suited for bluegrass lawns that have a greater need for nitrogen than other turf varieties.

      For Field Crops
      Pro-Booster 10-0-0 is perfect for periods of the crop’s life where nitrogen is a must. Many times during the growing season heavy rains or cold soil conditions can deplete or slow down the release of organic nitrogen from the soil. Plants that lack the necessary amount of nitrogen can become stunted and lose some of their natural resistance to environmental stress conditions, resulting in significant crop losses. Pro-Booster 10-0-0 can provide valuable crops with necessary N at critical times, to avoid stress from less than adequate nutrition.

      A word about Chilean nitrate
      The NOSB recommended that NOP implement a rule change prohibiting Chilean nitrate as a source of nitrogen on certified organic farms and it was scheduled to take place in October, 2012 but the NOP has not made any specific determination yet. It is uncertain if Chilean nitrate will eventually be prohibited on certified organic farms or not. However, Pro-Booster 10-0-0 can be made without Chilean nitrate upon request.

      For more information, download the product label pdf.

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