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.

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

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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.

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We recommend our Holland Secret 3-Part Fertilizer:

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 A container of Future Harvest Holland Secret GrowA container of Future Harvest Holland Secret MicroA container of Future Harvest Holland Secret Bloom

 

 CLICK HERE TO SHOP

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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:

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Per 4 liters (1 gallon) of water use:

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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. 

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For growing leafy greens we recommend increasing the nitrogen and lowering the phosphorus. 

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

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Don't worry about the flushing stage for vegetables, we only recommend flushing for crops that are meant for smoking!

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A group of plants being used in the Kratky Method

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The premise behind Kratky is you add a fairly weak solution of nutrients and as the water is used up the fertilizers will also be used up! This keeps the salinity from going too high and the grower won't have to do much further adjustment. 

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If you plants start wilting or the leaf tips turn brown, the solution has gone too strong (due to evaporation) and water should be added or your solution replaced. 

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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). 

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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. 

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If you grow plants with the Kratky method and are happy with it then by all means continue using it, there is no need for you to read any further.  However, if you want to maximize the potential of your growing set up, then you can read GROWING BEYOND KRATKY.  

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

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    Published by Loren Price

    Bio:
    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.

    E-Mail: loren@futureharvest.com

  • Feb 06, 2020
  • Category: Articles
  • Comments: 10
10 Comments
tomas peiser March 28, 2022

In this article you give us the formula for Leafy vegetables but do you have any others for peppers,, tomatoes, or beans?

Working with a small Kratky set-up for lettuce right now. I once it gets going i want to try something else.

Future Harvest March 28, 2022

Hi Tom,

The original 7:7:7 ratio has tomatoes and peppers in mind and Calnesium can be added that that but beans are nor really in this category as they aren’t nightshades and have different requirements.

For more advanced feeding instructions, here’s a post we did that’ll help you out: https://futureharvest.com/blogs/articles/growing-beyond-kratky (here look at the fruiting section as a starting off point for your beans).

Thanks and have a great day.

Jane October 17, 2022

Hello! Thank you for your post. I am just dabbling in hydroponics and am using the Kratky method. I bought a kit at a farmer’s market which included two small bottles of nutrients to be added while plants where sprouts. My tomatoes have pushed through and they have now flowered. But the bottom leaves are beginning to yellow which I’m reading may be a nitrogen deficiency. I have no idea what I should add bc I don’t know what was in the original bottles. Should I just mix the nutrients you suggested and empty and refill the reservoir adding the fertilizer to that? I did just order a PH meter and a TDS meter hoping to clarify my water quality. I’m a total newbie at this and at gardening in general so when it comes to fertilizer I have no clue what I’m doing!

FUTURE HARVEST October 18, 2022

Hi Jane! Thanks for your question! So I think you’ve likely rightly identified a nitrogen deficiency, with yellowing occurring on older growth first before progressing upward. Tomatoes are heavy feeders, requiring a lot of nutrients in comparison to leafy greens. Very smart of you to order an EC and pH meter! I would suggest draining your reservoir and adding Holland Secret Micro, Grow and Bloom in equal measure (as stated in the blog for , starting with the micro). Because you are using the Kratky method we’d still recommend the dosages of 7ml per gallon of each product while monitoring pH and EC. Aim for pH of 6.2-6.8 and an EC of 3.0. I would also highly recommend using Calnesium (calmag) in your solution because it will help to prevent blossom end rot, help to prevent calcium and magnesium deficiency, and encourage the uptake of other micronutrients. It could be that the nutrients in the kit are formulated for other crops that don’t require as much nitrogen, phosphorous and potassium (N-P-K). Hope this helps!

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