Comparison
Kratky vs Deep Water Culture for Potatoes
Kratky and deep water culture (DWC) both hold the plant above a container of nutrient solution. The difference is how the roots get oxygen. In Kratky, the solution level falls and leaves an air gap. In DWC, an air pump bubbles air through the solution so it can stay full. Kratky is simpler and silent, while DWC copes better with heat but needs power.
How each system works
Kratky: you fill the container once, and the plant drinks it down. As the level falls, the upper roots hang in moist air and take in oxygen there, while the lower roots keep drinking. You top up only a little, so the air gap stays. There are no moving parts.
Deep water culture: an air pump pushes air through tubing to an air stone in the solution, which releases a stream of small bubbles. The bubbles keep the water rich in oxygen, so the roots can sit in a full container. The level is kept up with regular top-ups, and many DWC growers change the solution from time to time.
In both systems, potato tubers form in the medium in the basket, above the solution, not in the water itself.
Side by side
- Oxygen: Kratky relies on the air gap. DWC aerates the solution all the time.
- Heat: warm solution holds less oxygen. Kratky roots in the solution suffer first in a hot spell, while DWC keeps adding air.
- Power: Kratky needs none. DWC needs an outlet and a pump that runs day and night.
- Noise: Kratky is silent. An air pump hums.
- Failure: nothing can break in Kratky. If a DWC pump or power supply fails, roots sitting in a full container can run short of oxygen quickly.
- Cost: Kratky is a container, a basket and nutrients. DWC adds a pump, tubing, an air stone and a check valve.
- Upkeep: Kratky needs careful, small top-ups. DWC needs the level kept up and the pump and stone kept clean.
What this means for potatoes
Potatoes are a long crop with a big plant, which tests both systems. In Kratky, the challenge is making one container of solution last through the season without flooding the air gap, and keeping the root zone cool. In DWC, the solution can stay full and well aerated through warm weather, which suits a big plant that drinks a lot, but you depend on the pump for months.
Neither system changes what the tubers need: a dark, loose medium in a deep basket, kept covered as the plant grows. Light leaks, a shallow basket or the wrong variety cause the same problems in both.
Who each one suits
- Choose Kratky for a first crop, for a quiet indoor space, where there's no outlet, or when you'd like something you can leave for a week.
- Choose DWC where summers are hot, if you want to keep growing through warm weather, or if you already run air pumps for other crops.
Setting up DWC for a potato
A DWC potato setup is a Kratky container plus aeration: the same deep, opaque container, the same basket of medium, and an air stone on the bottom connected to a pump outside. Put the pump somewhere its hum won't bother you, above the water level if you can. Keep the basket's base just touching the solution, as in Kratky, so the seed potato doesn't sit wet.
Turning a Kratky container into DWC
The two are close enough that you can switch. Add an air pump, tubing, a check valve and an air stone to a Kratky container, and it becomes DWC. Only keep the container full once the pump runs constantly. Roots that grew in a Kratky air gap aren't used to being submerged, so raise the level gradually over a few days rather than refilling all at once.
For the other systems, including ebb and flow and aeroponics, see hydroponic potato systems. For the Kratky setup itself, see how to grow potatoes without soil.
Sources
Questions about Kratky and DWC
Is Kratky or DWC better for potatoes?
Kratky is simpler and needs no power, so it's the easier first crop. DWC copes better with warm weather but depends on a pump.
Can I add an air stone to a Kratky container?
Yes. With a pump running constantly it becomes DWC, and you can keep it fuller. Raise the level gradually.
What happens if a DWC pump fails?
Roots in a full container can run short of oxygen quickly. Lowering the level to open an air gap buys time until the pump is fixed.
Do I need a check valve for DWC?
It's a good idea. If the pump sits below the water level, a check valve stops solution siphoning back into it when the power goes off.
Do potatoes form in the water in DWC?
No. In both systems the tubers form in the medium in the basket, above the solution.
Related Kratky potato guides
More on growing potatoes with the Kratky method, from the first sprout to the harvest.