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Fertilizer for hydroponics

What does a plant need?

Plants require additional nutrients for growth, like dissolved minerals and trace elements. Plants absorb the nutrients through their roots when they are dissolved in the water as ions. In hydroponic fertilizers, all essential ingredients must be contained in the fertilizer, since nothing can be additionally extracted from soil.

Macro elements - are needed in larger quantities

Nitrogen N, potassium K and phosphorus P

Secondary nutrients - important but needed in smaller quantities

Calcium Ca, Magnesium Mg and Sulfur S

Micronutrients - Traces, important for enzyme reactions

Iron Fe, copper Cu, zinc Zn, manganese Mn, boron B, molybdenum Mo, chlorine Cl, silicon Si - to name the most important

Mineral fertilizer

The nutrients in the mineral fertilizer consist of mineral salts. They are obtained from natural raw materials by special tretament and the composition is precisely adjusted. Mineral fertilizers for hydroponic applications contain everything the plants need. The nutrients are in such a condition that they can be absorbed and processed directly by the plants. The disadvantage is that the production consumes a lot of energy and resources. The advantage of these fertilizers is that they can be precisely dosed, act quickly and supply the plants optimally. For beginners in hydroponics, they are best suited.

Organic fertilizer

The nutrients in organic fertilizer are of plant or animal origin and are referred to as natural fertilizers. Some parts of the nutrients can be absorbed directly by the plants, others need to be decomposed by microorganisms, so that they can be processed by the plants. If highest yields are desired, organic fertilizers are perfectly suited. However, if sustainability and resource conservation are important, and if you are satisfied with good yields, organic fertilizers are also an alternative in hydroponics.

DIY - Produce organic fertilizer by yourself

From the conventional cultivation in soil the very good fertilising effect of compost is known. One can produce an own liquid fertilizer by means of a Bokashi bucket filling it with organic kitchen waste. Excluding oxygen, the organic material is converted by means of so-called effective microorganisms (EM®) and fermented to fertilizer. The EM are a mixture of photosynthetic bacteria, lactic acid bacteria, and yeasts. The produced liquid fertilizer is acidic and can be used very well in hydroponic systems.

Bokashi bucket

The pictures show the construction of a Bokashi bucket with well-closing lid, tap for the removal of the liquid fertilizer and drip strainer inside the container.

DIY - production of organic fertilizer for hydroponics | Bokashi


  • Insert the strainer into the Bokashi bucket and close the tap. Put the collecting container under the tap
  • To prepare, sprinkle a thin layer of EM on the sieve
  • Put small cut organic kitchen waste in the bucket and compress it to reduce the oxygen. Again sprinkle a layer of EM bacteria, close the bucket.
  • Fill the Bokashi bucket bit by bit. Always drain liquid fertilizer and use as fresh as possible.

EM Effective Mikroorganisms - Scanning Electron Micrographs

Effective Microorganisms EM are added as powders to the Bokashi bucket. The microorganisms are saturated and propagated on sugarcane molasses. To make the EMs visible, we are showing scanning electron micrographs (SEM).

The picture on the left shows the EM powder, in the round section in original, as well as an SEM image in 50x magnification. Good to see is the structure of the molasses. The EMs themselves are clearly visible in the right image as rounded shapes on the molasses support structure in 350x magnification - small and effective!

DIY - Homemade liquid fertilizer

Please note!

Nutrient solutions, fertilizers, test substances and test equipment in any form as well as contents of the Bokashi bucket

are generally kept away from children and not suitable for consumption!

Please observe the manufacturer's instructions.

Organic fertilizer for hydroponics

Measuring, setting and the right substrate

Add the self-made or purchased organic hydroponic fertilizer (observe manufacturer's instructions) to the nutrient storage tank - check the pH value with the pH meter and adjust to a pH of approx. 6,2 if necessary. Check with the EC Meter, if the nutrient quantity is ok. With organic fertilizer, an EC value of < 1500 µS/cm is sufficient (more info see Hydroponics - optimal growing condistions).

Microorganisms, such as EM, which can settle on substrate material, contribute to the nutrient solution being well absorbed and processed by the plants. Ceramic substrate behaves positively here.