Setting Up a Kratky Hydroponics System in 6 Easy Steps

In the “more than one way to skin a cat” department, Kratky hydroponics is a soilless growing method that is so simple in its design, it is the perfect introduction to the world of hydroponics.

Designed by Dr. Bernard Kratky at the University of Hawaii, the Kratky method is a system of passive hydroponics that requires no electricity, no pumps, and mostly common household items.

The Kratky method can be utilized on any scale. The most basic system requires only a one gallon reservoir, nutrient solution, a mesh growing vessel, grow media and a seed. In general with this method, for each plant grown, there should be one gallon of nutrient solution.

As the plant matures and imbibes the nutrient solution, there is an air space between the bottom of the pot and the top of the liquid. This is intentional as the roots require oxygen.

In a circulating hydro system, the oxygen is supplied with an air stone or by the air that comes into contact with the cycled nutrient solution. Once the nutrient solution has been depleted, it is time to harvest if it is a one-time crop like greens, or to be refilled if growing a fruit-producing crops like tomatoes or cucumbers.

Setting Up a Kratky Hydroponics System in 6 Easy Steps

With as many possible variations as there are growers, a Kratky system can be set up basically as follows:

1. Obtain a sealable container such as a five-gallon bucket or any reusable food-grade container with at least a one-gallon volume.
2. Drill a hole in the lid large enough to accommodate a mesh growing pot. If growing multiple plants, drill one per pot. These are usually about two inches in diameter, but could be bigger – smaller would not be very useful. A DIY cup could be fabricated with hardware cloth or poultry netting and wire.
3. Fill the reservoir with water and add a nutrient solution appropriate for growing your crop of choice.
4. Make sure that the pH of the solution is appropriate for crop growth as well. This will require a bit of research or assistance at your local hydro store or garden center to get the proper amendments.
5. Fill the mesh pot with a growing medium such as perlite, rockwool, or clay pebbles. Clay pebbles should not be used for crops with small seeds as they are more prone to falling through the crack into the reservoir.
6. Place a seed or a few seeds into each mesh pot. If more than one should germinate, thin down to the most dominate seedling.

Pros and Cons of the Kratky Hydroponics Method

Like any system, hydro or not, there are of course pros and cons to using the Kratky method. Its ease of use and low cost to set up make it an attractive system for both novice and professional growers alike.

It is also an easy demonstration of hydroponics for school projects or businesses to attempt. It is widely adaptable for every unique growing situation as almost anyone can come up with a container, water, and seeds. Like any crop, light is a must, and in low-light areas, supplemental lighting may be required.

Its drawbacks include those of other nutrient-cycling hydroponic systems, as well as those unique to a passive hydroponic system. It is difficult to grow any root vegetable or any long-term crop in a Kratky system. It is mostly conducive for lettuce and leaf crops. Some growers succeed in growing crops like tomatoes, peppers, and cucurbits with the Kratky system, but the method should be started with only the intent to grow leafy greens.

Kratky's biggest drawback is probably the fact that the stagnant water can become a breeding ground for many pests such as mosquitoes and algae. For this reason, it is best to use a container that is a solid color so as not to let in light.

The reservoir should be checked periodically for insect larvae and the nutrient solution should be changed if it is found to be supporting unwanted insect life.