top of page

How to fertilize my orchids?
         Before starting to talk about fertilizing properly, I would like to reflect on what it means to fertilize an orchid. For this, let's think about the human being; What happens to humans if they don't eat?    This answer will be the same as the question: what happens to an orchid if it doesn't eat? Fertilizer is the orchid's food. But let's go deeper; for human beings it is not enough to simply eat, it is necessary to ingest all kinds of nutrients and vitamins to keep the body healthy. It's the same thing with an orchid, if it lacks any nutrient, it won't grow, it won't flower,   it will get sick or even die depending on the nutrient that is missing . In this way, having beautiful, healthy orchids that bloom always involves the need for a well-made fertilization. 

Qual melhor adubo para minha orquídea

What is the best fertilizer?
      A good fertilizer depends on the quality of the raw material with which it is made. Let's take a practical example. One of the most important elements of abudo is nitrogen. But nitrogen can be added to the fertilizer in different ways: urea, ammonia, nitrates... they all release nitrogen, but the capacity of the plant to absorb each   one of them is different. This the manufacturer does not explain. And of course the price is different the easier and more available the nutrient is for the Orchid. This will be the biggest difference between one product and another.   Certainly, if you like your plants you won't want to give them just any fertilizer. 

Abubo para orquídeas

Organic or chemical fertilizer?
       Both organic and chemical (inorganic) fertilizers are used in orchid cultivation. In addition to the preference of each orchidist, there are some differences that you should take into account when choosing. There are even those who prefer to do both forms of fertilization together. Everything can give excellent results.
          Organic fertilizers usually have a slower and longer action, leaving only nutrients available for your orchid for a longer time. So they can be excellent for those who don't have time to fertilize the plants every two weeks. It also has the advantage of recovering the microbial flora of the vase.   The negative effect is a greater probability of the appearance of fungal and bacterial diseases, but this will depend more on the raw material used in the formulation. 

       The chemical fertilizers, on the other hand, are more concentrated and have a more exact formulation, even allowing to achieve a one-off effect that is desired in the plant. That's because we have nutrients that are more related to growth, others to rooting, flowering and so on. On the other hand, with chemical fertilizers it is also easier to intoxicate the plants, so it is necessary to follow the exact doses  (or even lower) than those indicated by the manufacturer.   It is also the type of fertilizer that will need to be applied more frequently to achieve optimal effects.  
      It should also be pointed out that chemical fertilizers are more related to the contamination of water resources.
     Organic fertilizers have been placed on the market with increasingly elaborate and precise formulations, so that they can also meet all needs the needs of plants.  
There is also technology that allows chemical fertilizers to be released slowly, improving their availability in the vessel without the need for constant application.
      increased use of organic and organic fertilizers such as gardens where normally children and animals like to play, and their ingestion does not represent a major danger, unlike chemical products effects can have very serious health consequences

Diferença de adubação organica e química

Aleksandro Zaslawski -

Foliar or root fertilization (conventional)?

      As the title suggests, nutrients can be absorbed both by the roots of the orchid and by the leaves themselves.
       foliar fertilization has grown more and more, at the same pace as the role of each fertilizer element is mastered.

      In foliar fertilization the replacement of nutrients is more effective, faster and more economical, as it avoids the waste arising from the dissolution of fertilizers in the soil  to become available for the plant.
       Nitrogen and potassium based fertilizers that are highly soluble can easily be washed out of the pot (leached out). Phosphate fertilizers can easily react with potassium, magnesium, aluminum and iron ions, becoming chemical solutions of no value to plants. The foliar nutrients, on the other hand, are mobilized directly to the plant leaf, which is actually the objective of fertilization, increasing the rate of photosynthesis in the leaves and stimulating  the absorption of nutrients by the plant root. Foliar fertilization is by far the most efficient. 

Adubação foliar

This does not mean that foliar fertilizers replace  the use of root fertilizers, but the use of foliar fertilizers has been shown to increase the availability of the main elements used in their root form.

Root x foliar absorption efficiency

Adubação de Orquídeas: foliar x solo
By Paulo N. Camargo and Ody Silva.

Absorption time after application

Como adubar uma orquídea

Law of Minimums
       Law proposed by the German scientist Justus Von Liebig (1803-1873), which states that plant growth is limited by the plant nutrient that is present in lesser relative quantity. This way, if an element is in deficient quantity, the development of the orchid will take place at the speed allowed by this lack. This implies that the lack of just one nutrient impacts the use of all the rest. There are stages in the life of a plant when the need for some nutrients exceeds its ability to extract them from the soil, even if these nutrients are abundant. The solution to ensure an adequate supply of missing micronutrients  is through foliar fertilization.

What influences the absorption of nutrients?
      The external factors that influence the foliar absorption of mineral nutrients are light, water availability in the soil, temperature, atmospheric humidity, winds and also the way of application of foliar sprays.
LIGHT-  The greater the light intensity, the greater the absorption of nutrients by the leaves. 
TEMPERATURE- The ideal is 22ºC to a maximum of 30ºC. The best time for foliar fertilizers or after 10 am is between 7 am and 10 am and after 10 am from 5 pm,
when the stomata are open. 
ATMOSPHERIC HUMIDITY - The higher the better,  because it keeps the cuticle hydrated and prevents evaporation of the applied solution, keeping it longer on the surface of the leaf._cc781905- 5cde-3194-bb3b-136bad5cf58d_Nutrients are generally absorbed when they are still wet on the leaf.
APPLICATION MODE-   Try to spray both the lower and upper surface of the leaf, with a fine mist, avoiding the formation of drops on the leaves. 
WATER IN THE SOIL- Foliar fertilizers should be applied when the plant is not capturing water at its maximum power. Foliar micronutrient applications are best applied when the plant is “calm” and full of water (turgid).

What is the composition of a fertilizer?
       We should consider the possibility of having two classes of nutrients in the composition: macronutrients and micronutrients. The division between milestone and micronutrients is based on the concentration present in the dry matter of the plants and has nothing to do with their order of importance. Any missing element will cause problems.  
The vast majority of fertilizers are composed only of the macronutrients N (nitrogen), P (Phosphorus) and K (potassium) the so-called NPK, but three more nutrients deserve to be mentioned,  are the so-called organic macronutrients” : carbon(C), hydrogen (H) and oxygen (O), which constitute most of the weight of the plant, which is found in abundance in nature and therefore is not added to fertilizers chemicals, but are abundant in organic fertilizers.
Currently, three more elements have been identified as macronutrients: Sulfur (S), Calcium (Ca) and Magnesium (Mg)

Macronutriente micronutrientes orquídeas

  As the elements S, Ca and Mg are not usually found in most fertilizers, in this case they must be added separately. Still, it's much better to choose fertilizers that have a complete formulation and have already been balanced for use. Always remember the excess of any element also harms the plant, sometimes preventing absorption and others due to direct toxicity. 
      The table on the side summarizes the function of each element and the symptoms of its deficiency.
Read more in the specific topic in the "Pests and Diseases" menu. 
      No rótulo dos adubos voce reparará que existem impressos tres numeros separados por um hifen, for example: 20-20-20, 30-10-10, among others.   These numbers are a reference to the concentration of N, P and K in the fertilizer in question. Thus,   a numbering 30-10-10 means 30% nitrogen, 10% phosphorus and 10% potassium. 
Those with a higher concentration of N are indicated to favor growth, of P to induce flowering and rooting, and those with a balance of the three elements for maintenance. 

Como adubar orquideas, microelementos, nitrogenio, amonia, ureia
Como adubar orquideas, adubo organico
      Above, the NPK concentration of some organic compounds. MO= organic matter (CHO).

        The figure above (on the left) shows something that no label or seller explains and that explains why the effects between different fertilizers, even with the same percentage of NPK, work differently with your orchids. The source of N is different in each fertilizer, and this difference brings different results. If you use a urea-based fertilizer (third column) N will hardly arrive in adequate amounts, as it will not stay long enough in the vase to be decomposed.   In addition, urea fertilizers are known to cause bud and root tip burns.  Studies in the 1960s already showed that nitric sources are far superior in promoting growth. 

        Other information that is often not present of the element will be available to the plant. So it's no use buying the product with the highest values. The amount available to the plant will be determined by the indicated dosage.  

      Lembre que altas concentrações de adubo desidratam a orquidea, causando a chamada "seca fisiologiaca ". If you want to ensure that you are not offering too high a concentration of fertilizer, you can invest in a device called a conductivimeter  (or EC meter). For orchids o ideal EC = 1.0 mS/cm and maximum EC of 1.4 mS/cm. 

      Finally speaking of micronutrients. The tables below summarize their importance: 

Como adubar orquideas, microelementos
Como adubar orquideas, microelementos

The secret of good fertilization for your orchids is the regular supply of all the nutrients it needs. Be systematic, strictly follow the label guidelines!!!

bottom of page