FFJ – Fermented Fruit Jiuce – The terp booster from Korean Natural Farming

Why do I need Fermented Fruit Juice?

The name says it all: FFJ is the sieved juice from homofermentative converted fruits which can be produced with the help of fermentation without the formation of alcohols. Depending on the time of harvest, these contain different proportions of relevant nutrients. (Ju-young Cho 1992)

In particular, these are the molecules that have not yet been completely broken down into their basic building materials (NO3-), such as amino acids and polysaccharides. These can be absorbed directly by the plant and save it, so to speak, binding energy, since it no longer has to synthesize it itself.

The homofermentative destruction (see LAB article for a detailed explanation) is particularly important here, as we only want to receive lactate and acetate in the first steps of lactic acid fermentation, as alcohol would kill the responsible microbes.

Which fruit can I use?

The most important thing in the production of FFJ is to use locally homegrown or at least Demeter / organically grown fruits, whereby the latter will perform significantly worse. That’s because for the planned fermentation we need a large number of microbes, especially Lactobacillus, which we get more by adding LAB. Natural yeasts and other microbes help in this process.

Once we have fulfilled this point, we can concentrate on the fruit. Nutrient analyzes can be used here, as these substances are then released into the liquid through micronization (decomposition of the plant tissue during fermentation).

High concentrations of potassium make apples, for example, a well-suited candidate for our FFJ. But it doesn’t just have to be the obvious fruits; vegetables like the pumpkin also achieve excellent results. In principle, all kinds of fruit can be used as long as they contain one of the 17 elements that can be used by plants.


Figure 1: Composition of mineral content of different apple varieties (Henríquez et al. 2010)

Immature or overripe – which is better in which phase?

When choosing the fruit, special attention must be paid to the degree of ripeness. This determines the timestamp of use in the growth cycle of cannabis in flowering phase. The flowering phase can generally be divided into three phases.

The first is the formation of inflorescences, paired with temporary, rapidly increasing elongation growth. Here the plant needs the highest amount of phosphorus in the flowering phase in order to produce enough inflorescences. Unripe fruits are the best choice for our FFJ, as they contain a high amount of oxalic acid. This organic acid is even better suited for dissolving phosphorus than sulfuric acid.. (Mendes et al. 2020)

Figure 2: High oxalic acid content in unripe bananas (Heather Wyman und Palmer 1964)

Overripe, but not yet bad fruit is excellently suited for use as an addition to irrigation water from the main phase, also known as “bulk weeks”, ie “rapid biomass growth”. These have the highest levels of organic acids, especially malic and citric acid.

Figure 3: Organic acid content in ripe banana (Heather Wyman und Palmer 1964)

These acids have already shown in several studies to significantly increase the dry weight of plants in particular in a concentration of 100mg/L (Talebi et al. 2014)

If you look at Figure 1, you will find that ripe bananas contain, for example, approx. 600mg / ml (6.2meq / 100g) of magic acid. This means that even small concentrations of FFJ are sufficient in the application.

But that was not all: Malic acid also strengthens the symbiosis with benign rhizobacteria such as B.subtilis FB17, which increases endogenous pathogen tolerance. These acids are normally produced in a complex manner by the plant itself. This also saves plant energy as ATP, which can be used for other processes. (Rudrappa et al. 2008)

How is FFJ made?

We’ve already covered the main part, but you need a few things first before you can start. Here is the list of ingredients you need:

  • The fruit (unripe or overripe)
  • A large mason jar (preferably two liters)
  • Cane sugar (for every gram of fruit, add one gram of sugar)
  • A rubber band
  • A cover, like a paper towel, that allows gas to be exchanged.
  • A bowl to mix
  • A scale

First cut the fruit into thumb-sized pieces and weigh them into the bowl. Now add the equivalent amount of sugar and a shot (2-4ml) of LAB.

Then mix it vigorously so that everything is moistened with sugar. You pour the mixture into the glass until it is too full. The edges / places with sugar on the outside of the glass can be cleaned with vinegar, otherwise ants or vermin could be interesting in the glass. You complete this with the paper towel and the rubber. Then it should be placed in a warm, dark place.

After 3-5 days, the solid mass should have lifted from the liquid. Simply sieve and saturate the liquid again with a little sugar.

How is FFJ used and applied?

Our FFJ is ready now. The leftovers can either be incorporated as head fertilization (fertilizer on substrate), but pay attention to the amount, otherwise you can catch unwanted guests.

You can also use the liquid normally in the maintenance spray (FPJ + brown rice vinegar + OHN), i.e. with rice vinegar and OHN. The concentration remains at 1: 500 as with FPJ. Read more about OHN in our first Korean Natural farming article.

Foliar fertilization should only be used if there are still small or non-existent blooms, as otherwise there is a risk of mold. As a rule of thumb, flowering week 2-3 is the last opportunity to apply FFJ to leaves.


Heather Wyman; Palmer, James K. (1964): Organic Acids in the Ripening Banana Fruit. In: Plant Physiology 39 (4), S. 630–633. Online verfügbar unter http://www.jstor.org/stable/4260273.

Henríquez, Carolina; Almonacid, Sergio; Chiffelle, Italo; Valenzuela, Tania; Araya, Manuel; Cabezas, Lorena et al. (2010): Determination of Antioxidant Capacity, Total Phenolic Content and Mineral Composition of Different Fruit Tissue of Five Apple Cultivars Grown in Chile. In: Chilean J. Agric. Res. 70 (4), S. 523–536. DOI: 10.4067/S0718-58392010000400001.

Ju-young Cho (1992): Cho`s Natural farming: Recipes and Instructions for use. Japan: Modern Agriculture.

Mendes, Gilberto de Oliveira; Murta, Hiunes Mansur; Valadares, Rafael Vasconcelos; Da Silveira, Wendel Batista; Da Silva, Ivo Ribeiro; Costa, Maurício Dutra (2020): Oxalic acid is more efficient than sulfuric acid for rock phosphate solubilization. In: Minerals Engineering 155, S. 106458. DOI: 10.1016/j.mineng.2020.106458.

Rudrappa, Thimmaraju; Czymmek, Kirk J.; Paré, Paul W.; Bais, Harsh P. (2008): Root-secreted malic acid recruits beneficial soil bacteria. In: Plant Physiol 148 (3), S. 1547–1556. DOI: 10.1104/pp.108.127613.

Talebi, Majid; Hadavi, Ebrahim; Jaafari, Nima (2014): Foliar Sprays of Citric Acid and Malic Acid Modify Growth, Flowering, and Root to Shoot Ratio of Gazania (Gazania rigens L.): A Comparative Analysis by ANOVA and Structural Equations Modeling. In: Advances in Agriculture 2014, S. 1–6. DOI: 10.1155/2014/147278.