Simple, Inexpensive Hydroponics: The Kratky Method

-Jordan Capps-

Howdy doody pandemic pals! I know these stay-at-home orders have thrown everybody for a loop, so I’d like to take the time to discuss the Kratky method, an easy–and cheap!–way to start a simple indoor garden at home. With just a few ingredients and a sunny window, you can be harvesting delicious leafy greens in almost no time! 

Named after B.A. Kratky, the kratky method is entirely passive, which means it requires no pumps of any sort. The nutrient solution remains stagnant, which is typically a dirty word, but as the plants drink from their small reservoir and the water level drops, an air gap grows between the nutrient solution and the plant itself, allowing the plant to breathe without oxygenating the reservoir. Simple! 

A one-gallon pickle jar is an excellent option for a reservoir, giving more pH and ec stability than a smaller quart jar, and allowing you to go the entire growth cycle of an average leafy green without refreshing the nutrient solution. Set it and forget it (for the most part)! Our 3.75 inch net cups nest just about perfectly within the opening to our gallon jars, so that’s the size that we’re gonna shoot for in this grow. If going with an alternatively sized jar, you want a net cup that fits completely within the opening, but doesn’t fall through into the jar itself. Some experimentation may be needed. Hydroton makes for a perfect medium in which to nest your starter plug of choice. 

Ingredients

• Pickle jar (1 gallon)
• 3.75 inch net cup
• HydrotonStarter plugs (Coco coir, peat, rockwool, etc..)
• Leafy green seeds (lettuces, spinach, herbs, etc..)
• Ph test kit (Ph test pen, indicator solution, or test strips)
• Ph up and/or down, depending on ph of water from your source
• Nutrient solution (Flora Series from General Hydroponics is a simple and affordable option)
• 10×20 flat tray and inserts
• Humidome

Instructions

1. Start seed in a moist starter plug, inside a humidome. Keep the plug consistently moist, misting if it gets dry. Once you have a sprout (~5 days,) you may remove the dome and continue misting the plug as required to maintain moisture.
2. Once you have approximately one inch of root coming out of the bottom of the plug, you may transplant the seedling into the net cup, filling in around the seedling with hydroton. 
3. Mix nutrient solution according to manufacturer’s instructions (Ph final solution to between 5.5 and 6.5) and fill jar so that solution reaches to just underneath the starter plug, but not touching the plug itself. You want the end of the root to be submerged in solution.
4. Watch your plant grow! As the plant grows and drinks from the jar, the solution level will lower itself, revealing more and more air space from which the plant can breath. The root growth should keep pace with the lower solution, leading to a completely hands-off grow!

Most lettuces and leafy greens should be ready for harvest before the nutrient solution is fully exhausted, but if deciding to grow vegetables with a longer harvest period, you’ll have to periodically replenish your reservoir. It’s really that simple. Thought you couldn’t get into hydroponics? Thought you didn’t have room in your life for any new hobbies? Think again!