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[Plant nutrients] The 13 most important ones and how to know if your plants are missing or excess

Surely you already know how important it is to fertilize your plants regularly.

And you may even be clear about the difference between nitrogen, phosphorus and potassium (the main nutrients in compost), and what happens when you go overboard with one or fall short on another.

But... did you know that for your plants to be healthy, up to 13 different nutrients are involved?

If one of them is too much or missing, that can lead to your plants losing vigor, and even getting sick and dying.

The problem is that it is not easy to understand:

  • What are these nutrients and what is the importance of each one.

  • How to know if your plants have a deficiency or excess of any of them.

  • The best way to prevent problems and that your plants are always healthy.

Do not worry, because we will explain all that here.

And we are also going to do it in the simplest way possible, so that you are able to understand what your plants need even if you do not have a degree in Chemistry.


Well let's go there.

The 13 essential nutrients your plants need to be healthy (and what happens if there is a lack or excess of any)

Not all nutrients are created equal.

Or rather: although all are important and necessary, there are some that the plant needs in much greater quantity than the rest.

Thus, from highest to lowest we have:

  • Main macronutrients.

  • Secondary macronutrients.

  • Micronutrients.

We’ll see them separately.

The 3 main macronutrients: nitrogen, phosphorus and potassium

1. Nitrogen (N)

Nitrogen is one of the essential nutrients that the plant use to develop. 

It is vital for the generation of chlorophyll (the substance that gives the green color to the leaves and that allows them to carry out photosynthesis).

If we have ... 

  • Excess nitrogen: when we use a very high nitrogen fertilizer, the plant develops many more leaves and stems, which also tend to have a very bright color (they are loaded with chlorophyll). The problem is that these leaves are very weak and sensitive to pests. Also, it produces fewer flowers.

  • Nitrogen deficiency: when it is low, the leaves become duller or develop yellow lines. This makes them more vulnerable to disease and pest attacks.

2. Phosphorus (P)

Phosphorus is one of the nutrients that the plant uses to develop flowers.

In addition, it also influences the growth of the root system, so the lack of this mineral will make the plant more sensitive to cold and drought.

If we have ... 

  • Excess phosphorus: this can block the absorption of some micronutrients (including iron or zinc), with the symptoms that this entails and that we will see later.

  • Lack of phosphorus: in addition to producing fewer flowers than normal (or not even blooming), it is common for purple tones to appear at the edges of the leaves.

3. Potassium (K)

Along with phosphorus, potassium is an essential macronutrient for plants to flourish and even to develop fruit.

Not only that, but it also intervenes in various vital processes.

Its deficiency can leave it more vulnerable to pests, diseases and extreme weather conditions.

If we have ... 

  • Excess potassium: like phosphorus, it can block the absorption of various micronutrients (which will weaken the plant).

  • Potassium deficiency: it is very common for the edges of the leaves to turn yellow.

Secondary macronutrients: calcium, magnesium and sulfur

4. Calcium (Ca)

Calcium is a nutrient that is usually found in most soils (except for some more acidic soils). 

It is involved in the formation of plant tissues and in root development, so its absence can cause weaker specimens to develop.

If we have ... 

  • Excess calcium: blocks the absorption of other nutrients, such as phosphorus, iron or magnesium.

  • Lack of calcium:it is common to see yellow leaves with dry tips. It can also affect the development of the fruits (which in many cases suffer from malformations).

5. Magnesium (Mg)

Like nitrogen and sulfur, magnesium is involved in the production of chlorophyll.

Its absence can lead to the appearance of streaks and yellow spots, very similar to those caused by a lack of iron (although in smaller quantities).

If we have ... 

  • Excess magnesium: it can affect the absorption of potassium.

  • Magnesium deficiency: yellow spots and edges appear on the leaves.

6. Sulfur (S)

This nutrient is essential for the formation of chlorophyll, as was the case with nitrogen and magnesium.

That is why its absence generates very similar symptoms.

If we have ... 

  • Excess sulfur: it can cause toxicity (the edges of the leaves turn yellow and dry out). In addition, it can also affect nitrogen absorption. But this problem is very rare.

  • Sulfur deficiency: something more common than excess. As with nitrogen, the lack of sulfur causes yellow spots on the leaves.


7. Iron (Fe) You have

surely heard the concept of “iron chlorosis”. A disease characterized by the fact that the leaves turn yellow (except for the veins, which remain green).

Well, the person responsible for this disease is precisely the lack of iron in our plants.

And it is that, although being a micronutrient it is not necessary that it be in a large quantity, it also intervenes in the formation of chlorophyll.

Hence, its lack can cause significant problems.

If we have ... 

  • Excess iron: very unusual. It produces the appearance of brown spots on the leaves.

  • Iron deficiency: its deficiency is more common in acid soils, and leads to iron chlorosis.

8. Zinc (Zn)

This micronutrient intervenes in the plant's feeding process, in addition to making it more resistant to low temperatures.

If we have ... 

  • Excess zinc: excess zinc is toxic to the plant, but it is very rare.

  • Lack: plants grow slower (or stop altogether) and leaves turn yellow.

9. Manganese (Mn)

Manganese is involved in several functions of the plant, including the production of chlorophyll.

If we have ... 

  • Excess manganese: affects the photosynthesis process and causes the weakening of the plant. It is very rare, but it can occur in soils with low calcium levels.

  • Manganese deficiency: occurs more in alkaline soils. Its lack causes symptoms similar to iron chlorosis.

10. Boron (B)

Boron is an essential part of plant growth and seed production.

If we have:

  • Excess boron: causes toxicity in plants, with symptoms similar to those of excess zinc or manganese.

  • Boron deficiency: it makes the plant develop more slowly and even the leaves are born with deformities.

11. Copper (Cu)

Intervenes in different vital processes of the plant, including photosynthesis.

If we have ... 

  • Excess copper: it can occur in substrates with high pH. Causes toxicity (mainly affects vegetables).

  • Copper deficiency: the lack of copper causes deformations in the plant and symptoms such as iron chlorosis.

12. Molybdenum (Mo)

This mineral is associated with nitrogen, so the symptoms of a lack of molybdenum are similar to those of this macronutrient.

The good news is that neither a lack nor an excess of molybdenum are common problems, because the minimum level that a plant needs is very low.

If we have ... 

  • Excess molybdenum: produces toxicity.

  • Molybdenum deficiency: it usually occurs in soils with low pH. The leaves develop yellow lines and spots.

13. Chlorine (Cl)

Intervenes in several vital processes of the plant. Fortunately, neither the lack nor the excess of this particular nutrient is usually a common problem.

  • Excess chlorine: produces chlorosis and can lead to necrosis of the leaves.

  • Chlorine deficiency: it is very rare. It is associated with the appearance of yellow edges on the leaves and wilting.

How do I make sure my plants have the necessary nutrients?

Surely now you are thinking something like:

But they are a lot of nutrients, and on top of that the symptoms of many are similar. Do I really have to watch out for all of this?”.

And the reality is that not necessarily.

It is good that you know the symptoms and that you are attentive so that, if your plants begin to develop them, you have an idea of ​​how to solve them (for example, trying to apply chelates of specific nutrients, amendments with lime for calcium, etc.).

But in many cases, the best thing you can do is make sure your plants are getting the right nutrients and that the soil conditions are correct.

Basically, the idea is to prevent rather than cure.

For that:

  • Use a suitable fertilizer: apply universal mixtures or specific fertilizers depending on the specific needs of each plant. 

  • Control the pH of the soil: as with compost, each plant grows better in more alkaline or more acidic soils (such as acidophilic plants). If you plant them in the garden, be sure to monitor the pH to avoid interfering with nutrient absorption.

  • Mixture of minerals in the soil: use substrates rich in nutrients and that meet the specific needs of each species.