The best way to fertilize will depend on what it is that you're planning to fertilize and what is in the fertilizer.
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So to answer the question, “What is the best way to fertilize?”, we really have to address two things:
1. What's in the fertilizer?
2. What is it that we're planning to fertilize?
Starting with “What’s in the fertilizer?”, it’s important to note that any bag of fertilizer that we look at has 3 numbers on it. And those three numbers represent Nitrogren, Phosphorus, and Potassium in that order. It’s always in that order. Those 3.
Nitrogen is responsible mainly for the greening and the overall shoot growth of the plant, whether that’s turf or ornamental plants.
Phosphorus is responsible for the establishment of the plants, whether that be new seed or new sod. In landscape ornamentals, it’s also responsible for blooming.
Potassium is important for the overall cell strength of the plant.
So turfgrass fertilizers, as a general rule, are in a rough ratio of about a 3:1:2. So meaning there’s about 3 times as much Nitrogen as Phosphorus, and about 2 times as much Potassium as Phosphorus.
Now, it’s always important to start with a soil test to really know what your turfgrass needs, but again this would be a very common ratio and it’s really important to note that it’s about the ratio and not necessarily the actual numbers on the bag.
For example, you might see a fertilizer that’s a 24-3-12. You might see one that’s a 24-5-11. But roughly speaking, those are about in that 3:1:2 ratio. A very common fertilizer for turf.
If we were starting a new lawn though or starting sod, again that Phosphorus, that middle number becomes really important. Those seedlings can’t reach the available Phosphorus in the soil.
So that’s where you might see something like a 6-20-10. And again, maybe it’s more 6-20-20. It’s not so much about the exact numbers, but just recognizing that when you see this center number being very high in comparison to the other two, that is mostly likely meant for starting a new lawn or new sod.
Landscape ornamentals on the other hand typically are more balanced. So their ratio would be often times a 1:1:1. Equal parts Nitrogen, Phosphorus, and Potassium. So again, very common to see products like a triple 15 (15-15-15), a triple 9 (9-9-9). And so while those numbers might be slightly different, the ratio is the same. That fertilizer contains equal parts of Nitrogen, Phosphorus, and Potassium.
And so that’s where, and we’ll talk in more detail later, we gotta know not just what these numbers are, but what’s the makeup of each of those. What type of Nitrogen for example? Or do these contain other things like Iron or Manganese or other nutrients in addition to these three that the plants might need.
Sometimes a fertilizer ratio is specified on soil test reports or in fertilizer recommendation sheets. The fertilizer ratio indicates the proportion of nitrogen, phosphate, and potash in the fertilizer product, and is determined by dividing each of the three numbers in the fertilizer grade (listed on the container) by the lowest number in the grade. For example, when each number in a fertilizer grade of 18-6-6 is divided by 6 (the lowest number in the grade), the proportion is determined as: three parts nitrogen to one part phosphate, to one part potash. Thus, the fertilizer has a 3-1-1 ratio.
If your soil test report recommends applying 1.5 lb of nitrogen, 0.5 lb of phosphate, and 0.5 lb of potash per sq ft, you should apply a fertilizer with a ratio of 3-1-1 since you need three times as much nitrogen as phosphate and three times as much nitrogen as potash. The simplest method of determining a ratio is to divide the weights of nitrogen, phosphate, and potash listed on the soil test report by the lowest weight of the three.
To determine a fertilizer ratio for a soil test recommendation of 1.5 lb of nitrogen, 0.5 lb of phosphate, and 0.5 lb of potash, divide the weight of each of the three nutrients (1.5 lb, 0.5 lb, 0.5 lb) listed on the report by the lowest nutrient weight (0.5 lb in this case).
1.5 ÷ 0.5 = 3
0.5 ÷ 0.5 = 1
0.5 ÷ 0.5 = 1
Thus, the fertilizer ratio that best fits this recommendation is 3-1-1. As demonstrated in the first paragraph, you can match the fertilizer ratio for this recommendation with a fertilizer grade by dividing each number in the fertilizer grade by the lowest number in the grade.
Determine ratios for the following fertilizer grades: 21-7-7, 22-6-8, and 18-5-9. Grade = 21-7-7Grade = 22-6-8Grade = 18-5-9 21 ÷ 7 = 3 22 ÷ 6 = 3.7 18 ÷ 5 = 3.6 7 ÷ 7 = 1 6 ÷ 6 = 1.0 5 ÷ 5 = 1.0 7 ÷ 7 = 1 8 ÷ 6 = 1.3 9 ÷ 5 = 1.8 Ratio = 3-1-1 Ratio = 3.7-1-1.3 Ratio = 3.6-1-1.8
As you can see from these three examples, fertilizer grades for certain products do not always match the exact fertilizer ratio you are searching for. Thus, the goal is to find a product with a grade that is as close as possible to the specified ratio.
Learn the basics of fertilizers, and you’ll help your garden grow as never before!
Fertilizer sections at nurseries, garden centers, and supply stores dazzle the gardener. The shelves are piled with boxes and bottles, the floors covered with bags stacked high. Labels identify the package contents as organic compost, rose food or vegetable food, lawn fertilizer or general-purpose fertilizer. In some stores, you’ll find bins filled with bone meal, blood meal, or hoof-and-horn meal―all labeled natural fertilizer. Choosing the right products to keep your plants healthy can often be a bit confusing.
Regardless of its type, any fertilizer you buy will come with information about the nutrients it contains, so you want to understand the N-P-K-ratio.
Prominently featured, the N-P-K-ratio is the percentage the product contains by volume of nitrogen (chemical symbol N), phosphorus (P), and potassium (K). A 16-16-16 fertilizer, for example, contains 16% nitrogen, 16% phosphorus, and 16% potassium. A 25-4-2 formulation contains 25% nitrogen, 4% phosphorus, and 2% potassium.
All fertilizers contain at least one of these components; if any is missing, the ratio will show a zero for that nutrient. (A 12-0-0 fertilizer contains nitrogen but no phosphorus or potassium, for instance).
Boxed, bagged, and bottled products display the N-P-K ratio on the label. For fertilizers sold in bulk from self-serve bins, the ratio is noted on the bin. One tip: Be sure to write the information on the bags you fill before you bring them home.
A fertilizer containing all three major nutrients is called a complete fertilizer; a product that supplies only one or two of them is an incomplete fertilizer.
Using a complete fertilizer for every garden purpose seems sensible, but, in fact, it isn’t always the best choice. If the soil contains sufficient phosphorus and potassium and is deficient only in nitrogen (as is often the case), you can save money by using an incomplete fertilizer that provides nitrogen alone (ammonium sulfate, for example). In some instances, complete fertilizers can even harm a plant. Exotic, bright-blossomed proteas, for example, will not tolerate excess phosphorus: they “glut” themselves on it and then die.
The inexpensive soil test kits sold at garden centers can give you a rough idea of the nutrients available in various parts of your garden. For a more detailed evaluation, you may want to pay for professional analysis, and there are mail-in versions of soil test kits, too. By revealing which nutrients may be lacking, testing can help you choose an appropriate fertilizer.
The various products labeled “general-purpose fertilizers” contain either equal amounts of each major nutrient (N-P-K ratio 12-12-12, for example) or a slightly higher percentage of nitrogen than of phosphorus and potassium (such as a 12-8-6 product). Such fertilizers are intended to meet most plants’ general requirements throughout the growing season.
Special-purpose fertilizers, on the other hand, are formulated for specific needs. They’re aimed at the gardener who wants a particular combination of nitrogen, phosphorus, and potassium for certain plants or garden situations. These fertilizers are of three general types.
One type, used during the period of active growth, contains largely nitrogen. Such products, with N-P-K ratios such as 16-6-4, are often used in spring, when you want to encourage lush growth or green up your lawn.
Another type is meant to stimulate root growth, stem vigor, and flower and fruit production. Fertilizers of this sort contain little nitrogen and higher levels of phosphorus and potassium; the N-P-K ratio may be 3-20-20, for example. These products are applied at different times and in different ways, depending on what you want to achieve. When you prepare a new planting area, for instance, you’ll work a dry granular fertilizer of this sort deeply into the soil, putting the phosphorus and potassium where roots can absorb them. The nutrients help strengthen the new plants’ developing stems and encourage the growth of a dense network of roots.
To promote flower production and increase the yields of fruit or vegetable crops, you apply the same sort of fertilizer to established plants after they’ve completed their first flush of growth. You can use either dry granules, scratching them lightly into the soil, or apply a liquid formula with a watering can or a hose-end applicator.
Courtesy of Urban Farmstead
A third group of fertilizers is designed for use on specific plants. These feature the N-P-K ratios determined to elicit the best performance from the particular plant, as well as other elements proven valuable to that plant. Such fertilizers are named according to the plant they’re intended to nourish. Especially useful are formulas for citrus trees and acid-loving plants such as camellia and rhododendron.
Recently, other such plant-specific fertilizers have appeared on nursery shelves, each claiming to be the best choice for a certain plant or group of plants; you may see several sorts of “tomato food” or “flower fertilizer,” for example. The jury is still out on the benefit of many of these products, and you will often do just as well to use a general-purpose type. The main distinction is often the price: the “special” formulas are usually costlier than general-purpose kinds.
Organic fertilizers are derived from the remains of living organisms; blood meal, bone meal, cottonseed meal, and fish emulsion are just a few of the many available types. Organic fertilizers release their nutrients slowly: rather than dissolving in water, they’re broken down by bacteria in the soil, providing nutrients as they decompose.
One of the many benefits of organics is they improve the “structure” of the soil the microorganisms that convert nutrients so plants can access them. Micronutrients are also often present, but they are not in synthetics.
Because these fertilizers act slowly, it’s almost impossible to “burn” or kill lawns or plants by applying too much (overdosing with synthetics, in contrast, can have potentially fatal results). Some manufacturers combine a variety of organic products in one package, then offer them for general-purpose or specialized use. Finally, they aren’t as water-soluble as synthetics, which means they won’t leach into waterways.
Two commonly used soil amendments―compost and manure―have some nutritive value and can be used as part of an organic fertilizing program. The N-P-K ratio of compost varies from 1.5-.5-1 to 3.5-1-2. Chicken manure’s N-P-K ratio ranges from 3-2.5-1.5 to 6-4-3; that of steer manure is usually a little less than 1-1-1.
Fertilizers containing seaweed are gaining favor with many gardeners. Besides providing nutrients in a form immediately available to plants, seaweed contains mannitol, a compound that enhances absorption of nutrients already in the soil, and various hormones that stimulate plant growth. And the carbohydrates in seaweed break down rapidly, nourishing soil-dwelling bacteria that fix nitrogen and make it available to plant roots.
Mixed with water and sprayed directly on foliage, seaweed-containing fertilizers can have dramatic effects in a matter of days. Plants green up and begin to produce new growth, and those that are weak stemmed and straggly straighten up and become stronger.
These products are derived from the chemical sources listed on the product label. They’re faster acting than organic kinds and provide nutrients to plants quickly, making them a good choice for aiding plants in severe distress from nutrient deficiencies, but they are more likely to “burn” the plant.
Synthetic fertilizers are sold both as dry granules to be applied to the soil and as dry or liquid concentrates to be diluted in water before application. In dry form, they’re usually less expensive than their organic counterparts. In some of the dry granular types (those known as controlled-release fertilizers), the fertilizer granules are coated with a permeable substance; with each watering, a bit of fertilizer diffuses through the coating and into the soil. Depending on the particular product, the nutrient release may last anywhere from 3 to 8 months.
Rachel Weill
Some synthetic products are packaged for special purposes; you’ll find spikes and tabs for container plants, for example.
Note that synthetic fertilizers usually do not contain any of the secondary or micronutrients mentioned above―but in most cases, these nutrients are already present in the soil. If a test indicates that some are missing, look for a fertilizer that provides them.
To balance your growing media pH, select a water-soluble fertilizer that works with your irrigation water.
There are two primary goals to keep in mind when selecting a water-soluble fertilizer for your facility:
1. Maintaining the growing media pH within an acceptable range, and
2. Supplying your plants with a sufficient amount of essential nutrients for good growth and flowering.
The “best” fertilizer to use on your plants is the one that not only supplies nutrients, but also complements the alkalinity and nutrient content of your irrigation water.
When discussing how water-soluble fertilizer affects growing media pH, it is important to understand that water-soluble fertilizer cannot be applied without irrigation water. The best guide when selecting an appropriate water-soluble fertilizer is to balance the proportion of nitrogen in the ammoniacal form (acid) against the irrigation water alkalinity (base). Although other factors affect growing media pH, research has shown that it is the balance between the ammoniacal nitrogen in the fertilizer and water alkalinity that has the greatest effect on growing media pH of long-term crops.
To understand how the alkalinity concentration in the water and the percentage of ammoniacal nitrogen in the fertilizer interact, picture a balance with water alkalinity on one side pushing the pH up, and on the other side, with the ammoniacal nitrogen pushing the pH down.
If either of these factors is out of balance, the growing media pH will be affected. For example, using a fertilizer very high in ammoniacal nitrogen (like 21-7-7 acid) with low alkalinity water (like RO or rain water) is very effective at driving the growing media pH down, because there is nothing to neutralize all the acidic hydrogens (H+) being produced through nitrification or plant uptake.
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Applying the right water soluble fertilizers can work wonders on field crops, in home gardens, and even for houseplants. Just as the fruits, flowers, and vegetables you grow need adequate light and water to thrive, they need essential nutrients, too. Providing macronutrients and micronutrients that plants can quickly and easily access can help you net better results overall. Water soluble fertilizers can boost both crop growth and the quality of produce. In fact, which nutrients you provide—and how and when you provide them—can affect everything from the health and size of cut-flower blossoms to the thickness of your lawn and the taste of fruit and veggies.
To understand what water-soluble fertilizers are and how they work, you first need to understand how plants access nutrients. Plants acquire nitrogen, phosphorus, potassium, and other essential soil-based elements through their roots. But it isn’t until you fully water plants—or they get a good, soaking rain—that soil-based elements become accessible to your plants’ roots. Once watered, your plants’ roots draw in much-needed moisture and the nutrients present in the resulting soil solution.
Typically available in pellets or granules, water-insoluble fertilizers don’t readily dissolve in water. Instead, these “slow-release” dry fertilizers offer nutrients very gradually. Slow-release formulas are worked into the soil near the plants they’re intended to feed. When it rains or when you water your plants, some of the dry fertilizer’s nutrients reach your plants’ roots.
For more information, please visit Blue NPK Compound Fertilizer.
Unlike their slow-release counterparts, water soluble fertilizers easily dissolve in water and allow for the instant uptake of nutrients. Some water soluble fertilizers are commercially available as concentrated liquids. Others are dry preparations. To use, you measure out some of the concentrated liquid or the dry ingredients and mix with water. Then, you simply water with the quick-release fertilizer mixture. Because the included nutrients are already in solution, they’re immediately available to plants.
Of course, the nutrient sources in fertilizer products vary widely. Some ingredients come from natural, organic sources. Others come from artificial, inorganic sources. Although such chemical-based liquid fertilizers often contain higher percentages of essential nutrients, it’s possible to have too much of a good thing.
From a plant’s vantage point, nitrogen synthesized from a nitrate form like ammoniacal nitrogen or calcium nitrate is just as useful as nitrogen derived from natural ingredients like bat guano or blood meal. The same goes for a potassium-containing potash (which is produced from potassium chloride) and potassium derived from natural sources like sea kelp. Nevertheless it’s best to avoid chemical-based liquid fertilizers.
Synthesized from chemical salts, inorganic fertilizers can negatively impact soil health and structure. With their continued use, accumulating sodium residues contribute to higher acid pH levels. This, in turn, repels worms and other beneficial soil-dwellers and can “lock up” your plants’ ability to uptake nutrients. Excess fertilizer salts also draw water away from plant roots—the cause of fertilizer “burn” injuries. In container gardens, excess fertilizer salts can lead to scale formation on the outside of the pots or the top of the soil. Eventually, the soil’s capacity to retain water also declines. Excess nutrients, such as soluble phosphates, can leach into area waterways, contributing to algae blooms and other harmful environmental effects.
Liquid fertilizers derived from natural sources are better for plants and the soil. They generally have a low salt index, meaning they’re less likely to cause fertilizer burn injury, alter soil pH, or disrupt soil microbial activity. Because they’re derived form natural rather than inorganic ingredients, they may also be chloride-free and include bioactive extras like amino acids, enzymes, and beneficial bacteria. These work to feed and support the soil itself.
You can use water soluble fertilizers on new seedlings, in well-established gardens, and everywhere in between. Want to kick-start very young plants? Start with a relatively weak nutrient solution. Want to induce early flowering or early fruit formation? Incorporate phosphorus and micronutrients like zinc and manganese into the fertilizer you apply. As all of your plants grow larger, you can provide a stronger, all-purpose mixture every couple of weeks. Ditto for routine feedings of houseplants and container gardens.
Water soluble fertilizers have many benefits—and some drawbacks. Their uniformity of application is one of their biggest strengths. Plants take in dry, slow-release fertilizers only when water is present in the soil. Unless this fertilizer remains evenly distributed, you may end up with some nutrient-rich pockets and other nutrient-poor areas. Plants near heavier concentrations of fertilizer salts are at greater risk of burning.
Conversely, water soluble nutrients are immediately available to plants wherever they’ve been applied. They are fast-acting but also short-lived. As a result, water soluble fertilizers are less likely to injure your plants, but they must be reapplied more frequently. Also, some of these cost a little more than dry, slow-release products. Still, being able to deliver specific nutrients exactly where and when you want to just might be worth it.
You can tell how much of each of the “big three” essential nutrients a liquid fertilizer contains by checking its label for three numbers, separated by hyphens. This is known as the NPK ratio. (Nitrogen, phosphorus, and potassium are represented as N, P, and K, respectively.) Say a product label shows a ratio of 3-2-6. That means the product contains 3% nitrogen, 2% phosphorus, and 6% potassium by weight. Just what do nitrogen, phosphorus, and potassium do for plants?
Nitrogen (N)—important for green, leafy growth and new shoot development
Phosphorus (P)—stimulates blossoming and fruiting; aids in new root development and prompts root growth
Potassium (K)—essential for critical functions like plant rooting and cell wall formation
Other important nutrients include but aren’t limited to:
Calcium (Ca)—plant building block bolsters strength of cell wall; neutralizes certain plant acids; aids in protein manufacture
Magnesium (Mg)—important chlorophyll component; helps make plant fats, starches, and more
Zinc (Zn)—needed for chlorophyll production as well as certain plant enzymes and hormones; helps plants set seed
Boron (B)—regulates cell growth and metabolic processes
Molybdenum (Mo)—essential for plants’ nitrogen uptake and use; helps plants make proteins
Manganese (Mn)—another chlorophyll component; assists with uptake of other nutrients
Liquid fertilizers may contain different combinations of these additional elements. Check your product’s ingredients list for references to secondary nutrients, micronutrients, or trace elements.
You can buy organic water soluble fertilizers in either dry or liquid forms. Often available as a powder or in pellets, dry preparations are intended to be measured out, mixed with water, and then applied to plants. Similarly, the concentrated liquid formulas also require some measuring, dilution into water, and mixing before use. Depending on the age and size of your plants, you may want to adjust your fertilizer-to-water ratio. Carefully read the manufacturer’s recommendation on the product label before you mix. Some commonly used organic nutrient sources follow.
Liquid kelp and seaweed preparations can really pack a punch since they often contain some nitrogen, potassium, and many of the harder-to-find trace elements all in one place. Because it prompts roots to grow, some gardeners use very diluted liquid kelp/seaweed solutions as pre-germination seed soaks. Whether you’re growing cherries or cherry tomatoes, the nutrients found in most liquid kelp preparations also can improve the quality of the produce. When applied during fruit development stages, liquid kelp/seaweed may increase fruit size and boost sugar content.
Most fish-based fertilizers are derived from whole fish or fish parts which have been ground up and liquified. These products are usually richest in phosphorus and nitrogen and also may contain some trace elements, beneficial enzymes, and amino acids. Because they may be lacking, some manufacturers add extra sources of potassium to their fish-based preparations.
Although it’s possible to make your own fertilizer teas from finished compost or vermicompost, you won’t necessarily know which nutrients and microorganisms are in your DIY concoctions. Commercial manufacturers offer at least some specifics about the myriad ingredients in liquid compost/earthworm castings tea. These products often contain important trace elements, beneficial bacteria, and fungi which can improve soil structure and health.
Created from a mixture of different nutrient-rich ingredients, combination liquid fertilizers usually contain staples like fish or bone meal, animal manures, and seaweed or kelp extracts. Sometimes marketed as fertilizer supplements, there’s a combination liquid fertilizer for nearly every use case. For example, calcium deficiencies contribute to flower drop, fruit dropping, and tomato blossom end rot, and calcium-rich combination liquid fertilizers exist to mitigate (or, better still, to prevent!) these issues.
You can apply water soluble nutrients with a simple watering can or even an elaborate irrigation system. Want to use water soluble fertilizers with drip irrigation? Just be sure that your chosen fertilizer is thoroughly mixed first. (You might also want to strain it to remove any potentially clogging particulates.)
Besides directing liquid nutrients to your plants’ root zones, you can also apply them to plant leaves as a foliar spray. For this use, check your product label for foliar application instructions and dilute water soluble fertilizers accordingly. Then, decant your mixture into a clean spray bottle. Foliar feeding is particularly helpful if you need to take quick, corrective action. (To avoid burning your plants, lightly mist foliage when the ambient heat and humidity are low—early mornings or evenings are best.)
Water soluble fertilizers provide a greater degree of control in terms of the strength of the nutrient solution you provide and the frequency with which you provide it. What’s more, because organic water soluble fertilizers also contain many essential micronutrients and even beneficial microorganisms, they feed your plants and the soil. That puts you in a better position to combat common issues like insect pests, plant pathogens, and adverse weather events like record heat and drought. Best of all, no matter what you grow, you can choose liquid formulas containing combinations of essential nutrients to meet any special requirement of crops.
Ah, the memories of those science classes! Remember sitting there, soaking up knowledge about photosynthesis? It was like learning the ultimate life hack of the plant world – turning sunlight into food.
But wait, did your teacher delve into the world of fertilizers? You know, those nutrient boosters that often get mistaken for plant grub? The official definition is “any material, organic or inorganic, natural or synthetic, which supplies one or more of the chemical elements required for the plant growth.”
Okay, that’s a little formal. Simply put, fertilizer is not plant food (they make their food!); its plant nutrients – like sulfur, calcium, nitrogen, etc. – required for the plant to grow, develop, and reproduce. There are different sources of nutrients that plants can use. It’s sometimes hard to know what to apply since there are so many options. Let’s go a bit deeper.
Types of Fertilizer
There are two main types of fertilizers: organic and inorganic. Organic ones are naturally derived, meaning they aren’t man-made. Inorganic fertilizers, on the other hand, are the factory-made, water-soluble counterparts.
While both have their merits, it’s important not to overdo the use of either type. Applying too much, or applying them when plants aren’t actively growing, can spell trouble for both your plants and the environment. Think nutrient runoff wreaking havoc on water quality and contributing to pesky problems like algal blooms. 
Regardless of the type of fertilizer, they can do damage to plants and the environment. Luckily, the same basic principles of selection and application apply to both organic and inorganic, or synthetic, fertilizers.
In the wild, plants get their nutrients from natural cycles. In developed areas, we use fertilizers to mimic the nutrients these cycles provide to wild plants. Developed, in this instance, refers to lawns, landscapes, and potted plants or raised beds. Fertilizers should be applied when the essential nutrients for plant growth are depleted, which is common in “developed” situations.
Fertilizers are similar in concept to a nutrient cocktail that plants use to support their growth and survival. Think of it as their vitamin regimen. The main players in this nutrient mix are nitrogen, phosphorus, and potassium – the trio responsible for keeping plants thriving. These are often referred to a macro nutrient – not because they are the most important, but they are typically required in the highest amounts when compared to the micronutrients (think calcium, iron, sulfur, etc.). Nitrogen (N) beefs up those leafy greens, phosphorus (P) digs deep for root health and flowering, while potassium (K) is like a plant’s immune system booster. Some fertilizers also contain micronutrients to support plant growth as well. Match those numbers to your plant’s needs and voila!
The Impacts of Fertilizer
But before you go wild with the fertilizer, hold your gardening gloves! Timing is everything. Just like sticking to a skincare routine, plants need a fertilizing schedule to keep them glowing. Applying fertilizers appropriately will give you the best version of your garden. Overapplication is financially wasteful and can damage your plants. The extra nutrients get washed away and enter water sources, which directly impacts public health and aquatic ecosystems, and not in a good way.
Picture this: Florida, a sunshine paradise, plagued by issues like red-tide and blue-green algae. Sound familiar? Yep, blame it on eutrophication – the fallout from excess nutrients in the water, courtesy of nutrient runoff. When aquatic plants overgrow from the nutrients in the water due to fertilizers, oxygen levels plummet, leaving marine life gasping for breath. Hence the harmful algal blooms.
Fertilizers are regulated materials that contain plant nutrients. On the label, there must be a nutrient analysis. This analysis is the representation of the nutrients as a percentage of weight. These materials are listed on the nutrient analysis, as well as any additional nutrients. So, it is important to be able to read and understand the label to choose the right one. Let’s learn how:
Nutrient Analysis – you can identify this by looking for the 3 numbers on the label. These numbers give the percentage of the three main nutrients, nitrogen (N), phosphorus (P), and potassium (K), by weight. So, think N-P-K when you see these 3 numbers. For example, a 100lb bag has 12-3-4, this means that there are 12lbs of N, 3 lbs. of P, and 4 lbs. of K.
Guaranteed analysis: this is the analysis by weight of each element present in the fertilizer, warranted by the manufacturer.
Total Nitrogen: the total amount of nitrogen expressed as a percentage.
Additional Macro-nutrients: additional nutrients displayed as a percentage by weight of the total amount of fertilizer.
Additional Micro-nutrients: micronutrients displayed as percentage by weight of the total amount of fertilizer. In Florida, our sandy soil may tend to have low levels of micronutrients, but your soil content should be determined by a soil test. Excess amounts of these nutrients can damage and kill plants.
Nutrient Sources: details where the fertilizer was derived from.
How do you know which fertilizer to pick, you ask? Start with a soil test. It’s like giving your plants a doctor’s check-up.
You can easily take a soil sample at home with a kit, or that can be sent to the UF/IFAS soil laboratory, where inexpensive testing is available to the public. Or you can pick up an online based soil test kit at your local Extension Office. Either kit is simple, provides specific instructions, and provides recommendations based on the specific plant and situation you note on the form. Based on the results, choose a fertilizer that caters to the specific nutritional needs of your plants.
Choosing the right fertilizer depends on a lot of factors. The type of plant, soil, and time of year are just a few considerations. Lawn fertilizers would burn garden plants because they contain too much nitrogen and sometimes other chemicals that are meant to control weeds, so it is important to do your research and pick the best fertilizer for your type of plant. One size does not fit all when it comes to fertilizing your plants.
Complete fertilizers: this type of fertilizer contains all three of the primary macronutrients – nitrogen (N), phosphorous (P), and potassium (K).
A balanced fertilizer contains equal amounts of nitrogen, phosphate, and potassium – like a 10-10-10 fertilizer.
It may be beneficial to apply this type of fertilizer if your soil lacks all three nutrients, but if your soil is rich in 2, applying all 3 nutrients could burn your plants and lead to toxicity as well as waste your money!
Incomplete fertilizer: a fertilizer that lacks one or two of the three major plant nutrients.
Slow & Controlled release: provide nutrients to plants over an extended period of time. The idea is to save money by fertilizing less frequently and prevent excess nutrients from entering waterways.
Read the label to find the percentage of slow – or controlled-release nutrients in the fertilizer, paying particular attention to the higher amounts of slow-release nitrogen.
In Florida, any fertilizer that is labeled “slow-release” or “controlled-release” must contain at least 30% or more slow- or controlled-release nitrogen.
Organic fertilizer: made from materials that are derived from plants and animals, like manure.
Inorganic fertilizer: materials that are mined or synthesized from non-living materials.
Dry fertilizer: made of powder or granular materials that dissolve in water.
Water-soluble/liquid fertilizer: water soluble powders or liquid concentrates that mix with water to form a solution.
Check out Types of Fertilizer – Gardening Solutions – University of Florida for more information.
By understanding the delicate dance between photosynthesis and fertilization, you can be a gardening guru and Florida Friendly. Remember, photosynthesis is the plant’s superpower, while fertilizer is its trusty sidekick, ensuring a healthy and flourishing garden. So, next time you’re out amongst the blooms, armed with your watering can and fertilizer in hand, channel your inner botanist and let the gardening magic begin! Happy gardening, folks!
If you want to learn more, please visit our website Potassium Fertilizer.