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Hydroponic system: the Kratky method

A horticulturist from the University of Hawaii, B.A. Kratky, has developed a method to grow plants in hydroponics in a passive way, without energy, which will be called the “Kratky method”. We will introduce you to this hydroponic system, its advantages and disadvantages.

Using the Kratky method to grow hydroponic plants

To set up a Kratky system, you must start by having a germinated plant. Use a “Rockwool cube” (a mineral fiber cube that retains moisture well), in a small pierced cup. Plant your seed, moisten it and wait for it to sprout. Once your plant has germinated well, the cotyledons have appeared and its roots are beginning to be visible underneath, you can let it soak in the nutrient solution.

Any closed container will do. The nutrient solution must be protected from air and light. A yogurt pot, for example, is fine: you make a hole in the lid to hold the cup and it’s perfect.

There are several principles to follow:

The support must be exposed to humid air, it must not soak.
The roots must remain moist, they must not dry out.
The roots must be soaked in the nutrient solution.

You can grow the classic plants. In particular, Kratky published an article on using this method to grow tomatoes.

Advantages of the Kratky hydroponic system

The advantages of the Kratky method are that it is very simple and passive.

A passive hydroponic system

A Kratky system does not need energy to operate, it is called “passive” or “non-circulating”. In general, a pump is needed to circulate the nutrient solution or to oxygenate it. There is no such thing here.

A very simple hydroponic system

More generally, the Kratky method requires very little equipment: a container is enough! You can recycle almost any plastic container into a hydroponic growing system. This will allow you, for example, to recycle your paint or yogurt pots. This is the great interest of this method: its simplicity.

The disadvantage: manually renewing the water

The main disadvantage of the Kratky method is the obligation to renew the nutritive solution regularly. Indeed, the plant will have, after a while, drunk all the water and risks to die. Beware of this pitfall.

To avoid this, it is interesting that the container is transparent or translucent enough to let you check the filling level at a glance.

To see the method in practice, here is a tuto from a blogger.