How to use the Kratky Method with 3-part Hydroponic Nutrient Solutions

What is the Kratky Method?

The Kratky Method is a simplified hydroponic system in which the plants are suspended above a reservoir containing a nutrient solution. As the plants access the water, the nutrient solution levels fall. As the solution levels get lower, the roots of the plant grow downwards to access more resources. This is merely a simplified introduction to the method, and those interested should research more thoroughly before attempting it. Today we will focus on applying our Holland Secret 3-part Fertilizer to the Kratky Method of growing using hydroponics. 

Hydroponics is a soilless growing medium in which you grow plants in liquid. Generally they are grown in a nutrient solution mixed with water.


What fertilizers should I use?

The fertilizers used for this method are relatively simple, consisting of a 4-18-38 blend, Calcium Nitrate, and Epsom salt. However, in Canada the 4-18-38 blend is not available resulting in those wanting to use this method often finding issues figuring out a proper feeding program. That’s where we come in! Using a 3-part system offers huge amounts of flexibility, as changing the ratios can allow for the replicating of most feeding programs.

We recommend our Holland Secret 3-Part Fertilizer:


What measurements should I use?

We did the hard part for you and looked at the amount of each individual nutrient that this feeding program is providing the crop and made adjustments accordingly. From that, this is what we recommend:


Per 4 liters (1 gallon) of water use:
7 mL Holland Secret Grow
7 mL Holland Secret Micro
7 mL Holland Secret Bloom 


Note: It is a lucky coincidence the measurements for each nutrient came out equal! When using a nutrient solution of another brand measurements may vary. 



Extra Tip:

For those of you interested in using the Kratky Method on tomatoes, we recommend supplementing with a Calcium and Magnesium nutrient as tomatoes have a high demand for Calcium. Do not add to the initial solution as it may be too strong for a young plant. Instead, add our Calnesium or Organical Magic nutrient once flowering begins. Add at a rate of 8 mL per 4 liters (1 gallon) for the remaining volume of nutrient solution (not the initial volume of solution you started the plants out with). 


Like other hydroponic methods, always remember to keep a close watch on pH and TDS levels (total dissolved solids). This is most important in warmer conditions as water may quickly evaporate and render the solution too strong which could damage the plant. 



Good luck! And remember you can always reach out to @futureharvestdevelopments on instagram if you have any questions or need advice.

    Published by Loren Price

    Loren, the Director of Fertilizer Technology at Future Harvest, grew up on a mixed grain and cattle farm in North West Saskatchewan. He went on to study biotechnology and worked in agrosciences in Saskatoon for several years before moving on to Future Harvest and the hydroponic plant food industry. Starting off in fertilizer production, his focus is now on fertilizer formulations and regulatory affairs. His areas of expertise include: agronomy, analytical chemistry, plant tissue culture, plant breeding, molecular biology, and plant nutrition. Outside of work, Loren collects vintage concert T-shirts and is an amateur craft brewer specializing in historical and lesser known styles of beer.


  • Feb 06, 2020
  • Category: Articles
  • Comments: 2
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Tammy Chevrier April 25, 2020

I am growing tomatoes, peppers, cucumbers & lettuce using the Kratky method. I purchased the Micro, Grow, Bloom & Calnesium recently. I am still in the learning stage and was wondering if the measurement of 7 ml for each of the three nutrients is the same for all the plants I am growing? Or should I be mixing a lighter solution for the lettuce? At 7 ml / 4 L what would the PPM reading be? Thank you.

Loren Price July 16, 2020

Without Calnesium a 7ml / 4 liter dilution will give a PPM of 910. With the additional Calnesium the TDS increases to 1170. While this should be good for the cukes, tomatoes and peppers it might be a bit rich for lettuce. Drop the Calnesium and drop the Bloom to 5 ml per 4 liters.

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