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Kratky method for growing cannabis

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captain

captain

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Joined
Apr 5, 2023
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I would like to experiment with growing cannabis using the Kratky method. Does anyone here have experience or can tell me what issues might prevent a successful Kratky grow? The basic Kratky formula is adding 10 grams of Masterblend (4-18-38), 10 grams of Calcium Nitrate (15.5-0-0) and 5 grams of Epsom Salt per 5 gallons of water. After blending these ingredients one at a time, with the Epsom Salt being the third ingredient to add, the PH needs to be adjusted to be between 5.8 and 6.2. After using tap water mixed with these ingredients, my PH is typically 7.1, so I add 10 grams of absorbic acid which eliminates any existing chloramine and lowers the solutions PH level to 6.0-6.2. This is an inorganic method, so more pure chemistry is involved.

Here is a basic Kratky grow video:

The beauty to this method is that it requires less attention to watering, and during flowering, need draining and cleaning the bucket and adding about a gallon a week of fresh solution. A quick rinse using hydrogen peroxide will keep the solution and changing will remove any condensed solids from the previous solution which can interfere with root health.

This is my first attempt using this method, so as all first timers, I expect to learn enough so my future attempts will have even better results. I would like input from others who have used this method, in case there are issues which I've yet to encounter and need to keep an eye on.

I am planning to use 16-18 hours of light on/6-8 hours of light off until the plant reaches 8 weeks of growth and I will switch lights to 12/12 for flowering. Make sure that the grow container, in my case a 5 gallon bucket, is translucent so no light can get to the roots and the solution which tends to promote algae growth. A good light is essential, and I am using a Spider Farms LED lighting system that give me a 4x4 sweet spot for light. I will still maintain a humidity sensor and humidifier, as I try to keep humidity between 60-70% and temps between 60-80 degrees.

I will try to post photos of progress using this method, but since I haven't germinated the seeds for my next crop, I'm sill 4-5 weeks away from moving seedling to 5 gallon containers to begin the Kratky grow.

All comments and advice are welcome.

Happy Growing!
 
I've grown DWC but always done it with air pumps to bubble the water. My main concern trying Kratky would be problems happening due to lack of aeration/oxygen in the water. I have seen forum posts where it was done successfully though.
 
Thanks for the reply. I have a couple of air stones/pumps if needed. I am going to try without added aeration at first but can add it later if needed. I like the idea of less daily attention, although I'm aware that as the plant reach full flowering, solution must be added to keep the bottom of the roots immersed in solution. I do outdoor grows each year, but I'm looking to do a winter indoor grow using the Kratky method. I have a friend who is a commercial grower who recommends DWC as a great way to grow cannabis at home, but suggests I will get similar results using Kratky. It will also be great to harvest in half of the time I give to my outdoor grows, which usually run over 6 months, but result in larger yields.

I hope to document my progress, so others who'd like to try growing via the Kratky method can benefit from my experiences.

Happy Growing!
 
Tracker said:
I've grown DWC but always done it with air pumps to bubble the water. My main concern trying Kratky would be problems happening due to lack of aeration/oxygen in the water. I have seen forum posts where it was done successfully though.
Click to expand...
Yes I think avoid root rot will be the buggy. Good luck sounds cool
 
I’ve found that passive hydro setups work better when I keep things super stable, especially pH and temps, and give the roots plenty of air space so they don’t stay soggy. If you ever scale up, checking out a light deprivation greenhouse can show you how controlled environments make plant growth way more predictable. Even small tweaks in airflow and light rhythm can save you headaches later.
 
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Kratky method is still being tested. I started with tomatoes, as they are similar to cannabis in that both are thirsty plants and consume more solution than other plants. My grow room is maintaining temps between 70-80 degrees fahrenheit, and 70% humidity. I did suffer some algae growth, which I was able to knock down using 3% H2O2 (hydrogen peroxide). All 4 varieties of tomatoes are growing well and all have established strong root systems.

Judging by the flowers I see, I'm about 2 weeks away from fruit. One significant change I made to the pure Kratky system was to add a reservoir containing an airstone and a pump and connected 6 additional buckets all containing tomato plants to the reservoir. I noticed early on that tomatoes grown in a hydro tower had significant growth advantages over a Kratky bucket which had no re-circulation and no aeration. Oxygenation is key and results in 30-30% greater growth. By having all the buckets sitting at the same elevation, all buckets maintain the same level of solution through hydro-static pressure, so I only add solution to the reservoir to raise the level in all 7 buckets.

I'll be shopping for clones over the next week, as I plan to plant 6 clones directly into Kratky buckets connected to another reservoir, and plan to finish them in about 12 weeks indoors. I hope to post photos and detail the progress, as this seems to be an ideal way to grow cannabis indoors just by paying attention to pH, solution level, and general room temperature. I plan to run lights on an 18/6 schedule switching to 12/12 after week 7, and harvesting after week 12.

From my research, you should plan on adding solution to cannabis plants grown in a Kratky container after 5-6 weeks of growth. Using a 5 gallon bucket, aim for about 6" of solution as a maintenance level and then add solution once a week to maintain this target level until harvest. This should keep the plants happy with the water roots submerged and the air roots maintaining a large enough buffer for the air roots to obtain oxygen.

HTH,

-- the Captain
 
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