All about plant fertilization

Best fertilizer for plants – [How and when to fertilize]

Fertilizer is one of the fundamental elements for the proper development of plants, at we are very clear about that. Plants need to absorb certain nutrients and minerals, which if they are not in the soil it is essential that we provide them through fertilizers.


Although no plant can live only based on fertilization, it needs other care such as proper watering, lighting, pruning, etc; providing extra nutrients will always help improve the development of any plant. On this website we specialize in giving advice on how to fertilize any type of plant. It is enough that you read any of our articles to verify it.

Fertilizer for plants

Here we will talk in a general way about fertilizers, we will give you the bases so that later you can understand much better all the articles that we have written and will continue writing.

Our latest articles

The rubber plant or by its scientific name Ficus Elastica is a plant that despite its tropical origin, its robust
Agapanthus is a plant of African origin, also known as Lily-of-the-Nile or the African lily plant. They have long leaves
Wisteria or glycine is a climbing plant that produces beautiful clusters of flowers that open in early spring. Its color
The curry leaf plant is native to India, where it is cultivated for its aromatic foliage and is used in
Zamioculca zamiifolia or zz plant as it is popularly known, is a tropical plant of African origin belonging to the
Daylilies are beautiful flowering plants that, despite their name, are not really lilies. They are actually perennial plants that belong

1. What is fertilizer


It is essential to start by defining the concept that has brought you to our website, what is a fertilizer? Surely you already have a sufficiently formed idea about the concept. But let’s look at some interesting definitions, I’ve pulled them from various reliable sources:

Fertilizer, natural or artificial substance containing the chemical elements that improve growth and productiveness of plants. Fertilizers enhance the natural fertility of the soil or replace chemical elements taken from the soil by previous crops.

The above is a definition given to us by the Encyclopedia Britannica, we are now going to a more specialized source on the subject.

Fertilizers are plant food: they provide nutrients for plants to grow and thrive. In addition to carbon, hydrogen and oxygen, which they obtain from the atmosphere and water, plants need numerous essential nutrients for their growth and health, which are provided by fertilizers.

With these two definitions that I have just given you, I think it is more than clear. In any case, I want to leave you one last thing that we have written from our website:

Fertilizers are nutrient-rich substances used to improve soil characteristics for better plant development. With them you can pursue different objectives depending on the type of plant in question; For example, improving fruit production, increasing the yield of a vegetable, or increasing the quality and quantity of flowers on a flowering plant. As you will see, it has uses on a large agricultural scale as well as being for domestic use in any orchard or garden.

You will have noticed that our definition was somewhat more extensive, it is that it is important for us to point out the uses that fertilizers have in areas such as agriculture. Thanks to fertilizers, crop yields are obtained that a few years ago were impossible to achieve.

1.1 Importance of fertilizer

The greatest importance of fertilizers lies in the fact that it allows us to cultivate our garden plants in a better way. I know that we all love the garden, but we must be honest the most important results of fertilizers occur in agriculture.

The increase in world population in recent decades brought with it a very important challenge for world agriculture. More mouths to feed brings with it the need to increase agricultural production. There are two ways to respond to this need:

  • The first option is to increase cultivated areas. Something that in highly developed countries is difficult to achieve, and that will generally go hand in hand with the deforestation of large forest masses.
  • The second option is to increase crop yields. That is to say that with the same planted areas it is possible to increase production, thus covering the need.

This second option is where fertilization comes in, and hence the great importance of knowing how to take advantage of it and use it correctly. Summarizing, I can mention these points for which fertilizers are so important:

  • Improves the quality of the soil: fertilizers provide essential nutrients for plant growth and improve the structure of the soil, which increases its capacity to retain water and nutrients.
  • Increases agricultural production: fertilizers allow higher crop yields, which is crucial to meet the needs of a constantly growing world population.
  • Reduction of deforestation: fertilizers can increase crop production on land already cultivated, reducing the need to deforest new areas for agriculture.
  • Improves the aesthetics of gardens: when used locally, fertilizers improve the health and appearance of plants in gardens, parks and public spaces.

2. Types of fertilizers


By classifying fertilizers we can divide them in different ways. Here we will talk about organic and inorganic fertilizers, a classification that is given from the components of the fertilizer. Then we will see slow-release and fast-release fertilizers, a classification given by analyzing how quickly nutrients are released. And we will end with dry fertilizers and soluble fertilizers, which are those that need or do not need water.

2.1 Inorganic Fertilizers

Inorganic fertilizers, also known as chemical fertilizers, are those that are produced through industrial processes and that contain nutrients in soluble forms that are easily available to plants. These fertilizers are usually cheaper and easier to apply, and can provide a rapid increase in crop production.

However, if used excessively, they can damage soil quality and the environment through the leaching of nutrients into bodies of water and the emission of greenhouse gases in their production and transport.

2.2 Organic Fertilizers

Organic fertilizers are those that are derived from natural materials such as manure, compost, food waste, and plant remains. These materials break down and release essential nutrients like nitrogen, phosphorus and potassium slowly, providing a sustainable source of plant nutrients. Organic fertilizers also improve soil quality by increasing biological activity and water retention, which helps maintain long-term fertility.

2.3 Slow Release Fertilizers

These types of plant fertilizers provide a steady supply of nutrients over a long period of time. They contain plant nutrients (mainly nitrogen) in a form that delays their initial availability.

Therefore, true slow-release fertilizers provide a sustainable and continuous supply of N for up to 4 months, even in uncertain weather conditions.

This slow release carries many benefits. Among them in logistics, since by providing nutrients for many months fewer applications are needed. On the other hand, the release is constant, there are no peaks, something good for any plant.

Advice: If you have come this far, surely you may be interested in browsing some of the sections of our website. You can find how to fertilize all kinds of plants:

2.4 Quick Release Fertilizers

These fertilizers are designed to quickly and efficiently provide nutrients to plants, and are often especially useful in situations where a rapid increase in crop production is needed.

They contain nutrients in soluble forms that are easily absorbed by plant roots. These nutrients are quickly released into the soil and are immediately available to plants. Therefore, crops can absorb the nutrients and use them for growth and development very quickly.

It is important to note that quick release fertilizers have many disadvantages. Because nutrients are released quickly, there can be nutrient losses through leaching and volatilization, something that doesn’t happen with slow release fertilizers. In the long term this will have a negative impact on both the environment and the quality of the soil.

2.5 Dry fertilizer

Defining this type of fertilizers is quite simple, since they are all those that are in solid form before any application or use thereof. Among all the dry fertilizers that we know of, there are powder fertilizers, granules, bars, etc.

That we call them dry fertilizers does not mean that after being applied you should not water the plant. Irrigation will always help a better dissolution of the fertilizer and a more homogeneous mixture in the soil.

2.6 Water soluble fertilizer

Water soluble fertilizers are chemicals that dissolve easily in water and are used to enrich the soil with essential plant nutrients. These fertilizers dissolve completely in water, making the nutrients immediately available to plant roots.

Water soluble fertilizers typically contain a combination of the three main nutrients that plants need to grow and thrive: nitrogen, phosphorous, and potassium (NPK). Additionally, some water soluble fertilizers may contain other nutrients and trace elements that are also important for plant growth, such as calcium, magnesium, iron, zinc, manganese, and copper.

Water soluble fertilizers are generally applied by diluting the product in water and then watering the plants with the resulting solution. This allows plants to absorb nutrients efficiently and effectively. Water soluble fertilizers are popular with gardeners and farmers because they are easy to apply and can provide additional nutrients in situations where the soil does not have enough nutrient quantity or quality for plants.

3. NPK fertilizer – Means, example, ratio


In the last section, where we talked about water-soluble fertilizers, we mentioned a very important concept that is NPK values. This is something that not all gardeners are very clear about, but if you are going to use commercial fertilizers it is essential that you understand.

Here we will see the most important aspects such as its meaning, ratio and some examples.

3.1 What N-P-K Numbers Mean

As this concept is fundamental to us, you can see that we give this definition in almost all of our articles. NPK is the acronym for the three main nutrients that plants need, which are:

  • Nitrogen (N): is an essential nutrient for the growth and development of leaves and stems of plants, which allows them to produce chlorophyll and perform photosynthesis. It is also important for the formation of proteins and enzymes in plants.
  • Phosphorus (P): This second nutrient is important for the formation of strong and healthy roots in plants, which allows them to absorb water and nutrients from the soil more efficiently. It is also essential for the production of flowers and fruits in plants.
  • Potassium (K): the third but not least helps in the production of flowers and fruits in plants. It also helps plants regulate the opening and closing of stomata, which allows them to regulate water loss and maintain their hydration.

What the three NPK numbers represent is the percentage by weight of each of these nutrients that the fertilizer contains within its composition. You will understand it better with an example.

3.2 NPK example

Let’s look at a quick example. If you have just bought a fertilizer whose NPK numbers are 15-5-25, it means that within the composition of the fertilizer you have:

  • For each kilogram of fertilizer there is 15% Nitrogen, that is to say 150 g in 1 kg.
  • 5% phosphorus, that is to say 50 g in 1 kg.
  • And finally 25% potassium, which results in 250 g in 1 kg.

If what you have is a 10-10-10 or 20-20-20 fertilizer, both of which are fairly common fertilizers. What you have is what we call a balanced fertilizer. We call it that way because it contains the same proportion of the three main nutrients in a balanced way.

3.3 NPK ratio

The dose to apply will depend on the concentration of nutrients, the plant you need to fertilize and the characteristics of the soil. It is something that cannot be answered in a general way, but each special case will have a different answer.

To know what dose you should apply, it is better to search among our articles if you find a post about the plant that you are going to fertilize. If you can’t find it, I can simply recommend that you follow the recommendations on the fertilizer container.

4. Fertilizing plants – How to do it


To fertilize correctly, the first thing we must do is find out the type of fertilizer that is best suited to the plant in question. Each type of plant behaves better to certain fertilizers, so you should start by informing yourself. I recommend that you search our blog, it is very likely that we have already written an article.

If you already know which fertilizer to use, and it is commercial, it is best to follow the instructions on the bottle. In any case, I recommend that you use slightly lower doses than those recommended in the instructions, since they are generally somewhat high.

It is essential not to apply exaggerated doses, since if we go too far we will burn the roots, killing the plant. On the other hand, the excess of nitrogen in the substrate makes the plant more prone to pests. Insects like thrips, mealybugs, and aphids love this chemical element.

4.1 How to fertlizer step by step

Regardless of whether the fertilizer is liquid, foliar, granular, powder, or any format, do not apply it without first taking care of the plant a bit. Follow these steps:

  • Start by removing dead branches and faded flowers, letting fresh leaves get more sunlight and ensuring nutrients flow into new growth.
  • If the fertilizer is foliar, you can now apply the fertilizer. If, on the other hand, the fertilizer must be applied to the soil, you must carry out the following step.
  • It is very important that you cultivate the soil by stirring it gently, making sure not to damage the plants or roots. Once the soil is well moved, you can distribute the fertilizer evenly, avoid the fertilizer touching the plant.
  • Finishing the application of the fertilizer it is time to carry out a good irrigation. This will help the plant to absorb the fertilizer.

You already know in a general way how to apply a fertilizer, let’s see now when it should be fertilized.

5. When to fertilize plants


Defining in a general way the ideal moment that plants should be fertilized is something very difficult. Each plant has different characteristics for what it needs, so not all of them should be fertilized at the same time.

Again, what I have to do is recommend that you look for specific information depending on the plant you want to fertilize. In any case, since I don’t want you to leave empty-handed, we will do a somewhat general analysis.

To be somewhat more specific and for the information to be useful to you, we will divide the analysis into four types of plants; shrubs, floral, fruit and vegetable plants.

5.1 Perennials and shrubs

In plants such as shrubs, it is essential that you fertilize at times when the plants are active, and can thus absorb nutrients. That is to say that you must fertilize when the plant is in an active stage of growth.

Shrubs are usually in an active stage during spring. So the best time to fertilize them will be at the beginning of it. Depending on the case and the type of bush, some benefit from fertilizing in the summer. And even in certain cases it can also be fertilized after flowering.

You should always keep in mind to avoid fertilizing when the plant is not active, or in drought stress processes. If the weather is too dry, do not apply any fertilizer, since it will be difficult for the plant to absorb the nutrients.

5.2 Fruit trees

As we saw in previous sections, each nutrient has a different effect on the plant. While nitrogen helps vegetative growth, phosphorus is important in photosynthesis and potassium is responsible for feeding the fruits. To correctly fertilize fruit trees you must keep these concepts in mind, having to apply each nutrient at the best time. Let’s see when it is:

1st ► Nitrogen, during the spring, during the vegetative development of the tree

2º ► Phosphorus, in flowering and fruit set

3º ►Potassium, once the hardening of the fruit has occurred, the tree has the greatest potassium needs to develop the fruit.

When to fertilize Fruit trees

The previous graph should help you understand better.

5.3 Vegetable garden

We need vegetables that grow quickly and vigorously. For this reason, I recommend that you fertilize at these times:

  • Before planting: It is important to prepare the soil before planting. Depending on the characteristics of the soil, it may be advisable to start fertilizing before planting. If the soil is poor in nutrients, you can add fertilizer or compost. If the soil is rich in nutrients, it will not be necessary to fertilize before planting.
  • During growth: Plants need additional nutrients during growth to stay healthy and produce a good harvest. It is generally best to fertilize plants every four to six weeks. However, this can vary depending on the type of plant and the type of fertilizer you are using.
  • After harvest: After harvest, you may want to fertilize the soil to replenish lost nutrients. If you are planting a fall crop, it is important to fertilize after the summer harvest to prepare the soil for the next crop.

Keep in mind that these are general guidelines, so each vegetable in your garden may need nutrients at other stages.

5.4 Flowers plants

The fertilization of floral plants must be carried out depending on the type of flower in question. There are plants that bloom in spring, others in summer, in autumn and even in winter. As well there are annual, perennial flowering plants, flowers that grow from new growths or those that grow from branches of the previous season. All these factors influence fertilization.

In general, I can recommend the following:

  • In perennial flowering plants or ornamental grasses fertilize when growth resumes, usually in spring.
  • Plants such as rose bushes should be fertilized from the month of May, and never after the month of July. You should never encourage the rose bush to put out new shoots when frost is about to arrive.
  • Flowering plants that develop from bulbs should be fertilized as soon as they start to grow. Generally it should be in spring.

Within our blog there is an extensive catalog on fertilization of floral plants, visit our blog to find your plant. 😉

6. How often to fertilize plants


Again we find ourselves with a question that is difficult to answer in a general way. There are several factors that influence the regularity of fertilization, among them the plant, the type of soil, the climate and the type of fertilizer.

Let us analyze some particular cases.

6.1 Indoors plants

When what we have are indoor plants, that is, those that grow in pots, obtaining nutrients is limited to the soil that is in the container. In nature, soil nutrients are renewed with the decomposition of organic matter such as vegetables, insects or general wildlife. But that’s not the case with potted soil.

This situation gives us as a result that potted plants need more regular fertilizations than outdoor plants. But answering exactly what regularity they need again comes from the same factors that we mentioned before (type of plant, soil characteristics, climate, type of fertilizer).

  • Type of plant: larger plants generally tend to produce more flowers and fruits, so they need more regular fertilization. While the smaller plants that can grow in poorer soils are content with less frequent fertilizations.
  • Soil: If the soil is sandy, it has a lower nutrient retention capacity, so more frequent fertilizer applications are needed. While in dense soils the nutrients are retained in a better way, so you don’t need to fertilize very often.
  • Climate: Plants are usually dormant in winter, so you don’t need to apply much fertilizer at that time. On the contrary, in spring and summer is when more frequent applications are needed.
  • Type of fertilizer: The last factor is the type of fertilizer. If you choose to use the slow-release ones, one application throughout the season may be enough. While if you use liquid fertilizers you should make several applications during the spring and summer.

As you may have seen, they are all general advice. Again I recommend you look for the particular information of the plant that you need to fertilize.

6.2 Vegetable

How often you should fertilize your vegetables depends on several factors, such as the type of crop, the type of soil, and the type of fertilizer you’re using.

Advice: If you continue here, do not leave without first browsing any of the sections of our website. You can find how to fertilize all kinds of plants.:

In general, vegetables need regular nutrients to grow healthily and produce a good harvest. If you are using organic fertilizers, such as compost, manure, or green manure, you may need to apply them once or twice a year, depending on the quality of the soil.

If you are using chemical fertilizers, you may need to apply them more frequently, as they dissolve faster in the soil. In general, it is recommended to fertilize vegetables every two weeks or every month, depending on the type of fertilizer and the needs of your plants.

7. How much fertilizer per plant


Determining how much fertilizer to apply again will depend on a few factors. In order to determine the amount of mini-maintenance fertilizer you must be clear about the following:

  • Characteristics of the plant: there are plants that need soils very rich in nutrients, which will need different amounts of fertilizers than those plants that grow perfectly in poor soils.
  • Type of soil: it is important that you know the composition of the soil if you want to make a good fertilization. Knowing the nutrients that the soil has with the fertilizer, you should only replace the nutrients that the soil does not have.

Given that analyzing this point in a general way is very complicated, since each plant has its specific requirements, what I will do is leave you with some fertilizer calculators. Once you are clear about the previous points, you will be able to calculate how much fertilizer they need.

Use them and then tell me if they have served you. If what you are going to do is simply apply fertilizer in your garden, do not get complicated using the previous calculators. Just read the instructions for use of the fertilizer container, or failing that, look for more specific information on our blog. 😉

8. Over fertilization of plants


I didn’t want to finish writing this page without touching on the subject of overfertilization. You must bear in mind that the amount of fertilizer that you apply is not directly proportional to the size of the fruits, flowers or foliage in general that you are going to obtain. Just as you can end up with serious health problems from eating too much, the same goes for plants.

Overfertilization, along with excess watering, are two of the most common causes of plant disease. Fertilizing well will bring very positive aspects to your plants, and inversely if you do it excessively. On this website we have this saying “it is easier to solve a problem of lack of nutrients than to try to save a plant with excess nutrients in the ground”.

On this website we have this saying “it is easier to solve a problem of lack of nutrients than to try to save a plant with excess nutrients in the ground”.

Too much fertilizer causes plants to grow weak and too tall. The tips of the roots can burn due to the high level of salts that these substances contain. In short, overfertilizing any crop can make plants much more compromised in the presence of disease.

The best solution for these problems is to prevent them, since when you detect them it may be too late to fix it. And to prevent this situation, you should only apply the amount of fertilizer that the plant needs. If the fertilizer package says to apply 2.50cm3 for each liter of water in irrigation, it is better to use a little less. Test with 1.50 cm3 and observe the results.

8.1 Symptoms of excess fertilizer

As with any type of problem in your garden, before trying to fix it, we must first be sure of the cause of the problem. Many times it happens that the day after fertilizing your plant undergoes some change, and instantly we already think that it is the fertilizer’s fault. But it may not be so, make sure and then act, otherwise trying to fix it can make the situation worse.

Among the most common symptoms that can appear when we overfertilize are the following:

  • Withered leaves, with burnt edges or spots
  • Massive leaf drop
  • Lack of plant growth.
  • Flowers that do not open

Likewise, the presence of pests such as aphids or mealybugs can make us think about the possibility that an excess of fertilizer has been given to the plant.