It -is all it’s Kratkyed up to be. No electricity, fancy equipment, or soil is needed. You set up the “system” and leave it be. You can grow a head of lettuce for a dime. Using the Kratky method requires:
₀ A container
₀ Water soluble fertilizer
₀ A way to suspend and anchor the plant
₀ A plant with roots
The container can be up-cycled material. I have used: liter soda bottle, ice cream buckets, Tupperware, and other food buckets. The container needs to be waterproof (plastic is easiest), food grade and stop light from getting the roots. Spray paint translucent containers to prevent algae growth.
Net pots or hole-punched solo cups are a cheap and easy way to hold the plant. To keep the plant from sinking and to cover the roots use: perlite, vermiculite, or coco coir. To suspend your net pot or cup you can use a lid or styrofoam (make sure that the styrofoam is held by the edge of the container). I use rock wool to seed plants. A tray of vermiculite can be used to seed as well. Once the plants have roots you can add them to your Kratky container, with the fertilizer solution covering the half the plants’ roots.
Remember to use water soluble fertilizer. Water should be the PH of plant requires. Fertilizing solutions and recipes for specific plants can be found at any hydroponics store. Do not use fertilizers that depend on bacteria to be broken down. Fertilizers that are meant for soil, such as Miracle Grow, will contain nitrogen that will not be utilized. A good rule of thumb is to use fertilizer marked for hydroponic, ebb and flow, or NTF systems.
There is an order to mixing fertilizers. Epsom salts and base fertilizer can be mixed in separately first. Mix the solutions or powdered fertilizer components, until, the solution is homogeneous. Nitrogen and then Calcium should be the last thing that you mix into your solution. Several theories have been explained to me. I remain unsure, but the best explanation was that the nitrogen and calcium need other chemicals to bind to or they evaporate or sink. This is called “fall out”. If nitrogen or calcium fall out of a fertilizer solution, plants will be stunted.
My Experience with Fertilizer
Most suppliers require a premium or a large purchase. I use industrial fertilizers from. I can order smaller amounts of fertilizer. They are the least expensive with the best results, in my experience. Hydro – Gardens website is . . . awful. I use their catalog. Daniel calls them to place his orders, as he does not plan as far ahead. I buy my Epsom salts from the grocery store, as it is cheaper and the same chemically.
If I had it to do again, I would buy the calibration weight and the four-minute auto-turnoff. The scale calculates ounces and grams to the tenth; which is what you will want, for small batch growing. I measure in order my ingredients. Mix them into a gallon container with a lid. I shake the container until I can no longer see any of my powdered fertilizer. Once I have all the components mixed I add the solution to a larger bucket or reservoir and mix the new solution into the water. I adjust the PH to the plant’s needs. From there I fill the containers I am using for my Kratky system.
Recipes are Guidelines
I use Hydro-Gardens suggested recipes (found in their catalog) with only small variations. In Arizona, there was a lot of calcium in the water. I reduced the calcium in the recipe. In Wyoming, I do not need to add as much nitrogen. The PH is 7 in Wyoming. In Arizona, it was 5. I did not have to adjust the PH is Arizona because once I added the fertilizer I was at a perfect PH.
Observing your plants will tell you how you need to adjust your recipe. You will likely still get growth, but your plants could do better with the best fertilizer recipe. For example, if your plants are vivid green you may need to cut down on nitrogen. If the leaves are curling you may not have enough calcium.
Why it Works
Bernard A Kratky rediscovered this method. I say rediscovered because it is speculated, The Hanging Gardens of Babylon, used this method. Mr. Kratky found that plants have roots that need oxygen. Hence, with an air gap providing oxygen, plants grow faster. Therefore without all the downfalls of soil gardening plants are able to grow faster. Basically, the plant pulls the needed nutrients and oxygen without interference
What to Plant
In my mind lettuce is the best crop for a Kratky Float Table. Other short-term green plants with low nutrient draw are good choices too. For example: Bac choy, celery, and Chinese cabbage. If you prefer to harvest young mint and basil the Kratky method will work too.
I jump-start my dutch bucket plants using the Kratky method. However, dutch bucket plants are flowering, fruiting plants. For example: cucumbers, tomatoes, peppers, and squashes. Fruiting plants nutrient demands change as the plant flowers and fruits. A dutch bucket system has a reservoir that’s fertilizer solution is changed for each stage of the plant’s development.
What Not to Plant
₀plants with rhizome
₀plants with long growing seasons and high nutrient draws.