What is the Kratky method?
The Kratky method is a non-circulating hydroponic technique. The plant begins with roots near the nutrient solution. As water level drops, an air gap forms and oxygen reaches part of the root system.
It is popular with beginners because it removes pumps, air stones, tubing, and timers from the first build.
New full guide: follow the step-by-step Kratky Method for Beginners article if you are setting up your first jar.
A simple Kratky jar build
- Choose a wide-mouth jar or opaque container.
- Add a net cup that fits the lid opening.
- Start a seedling in a plug or place a young transplant in the net cup.
- Mix nutrients in water according to the label.
- Set the initial water level so the plug or young roots can reach moisture.
- Block light from the nutrient solution with an opaque wrap or container.
- Let the water level fall naturally as the plant grows.
Beginner warning: do not keep refilling to the top after roots develop. The air gap is part of the system.
Best plants for Kratky
| Plant | Why it works | Difficulty |
|---|---|---|
| Lettuce | Fast, compact, forgiving. | Easy |
| Basil | Useful harvests and clear growth signals. | Easy |
| Mint | Vigorous and resilient. | Easy |
| Bok choy | Quick leafy crop for small containers. | Moderate |
| Tomato | Needs more light, support, and nutrient control. | Hard |
Troubleshooting checklist
- Algae: cover the container and reduce light hitting water.
- Wilting: check water contact for young roots and light distance.
- Yellow leaves: review nutrient strength, pH, and plant age.
- Brown roots: check smell, temperature, and oxygen access.