Learn Kratky Hydroponics

Fourteen short lessons take you from never having grown in water to harvesting your own Kratky plants. Read them in order and set up one container as you go.

The lessons

1. How the Kratky Method Works
   What happens inside a Kratky jar, and the three rules every lesson builds on.
2. Choose Your First Kratky Plant
   Why leaf lettuce is the easiest start, and what to save for later.
3. Gather Your Kratky Supplies
   The short list of what you need, and what can wait.
4. Pick a Kratky Container
   Dark walls, a good lid and the right size for your plant.
5. Start Seeds for Kratky
   Sowing in rockwool or plugs, and knowing when seedlings are ready.
6. Mix the Nutrient Solution
   Choosing a hydroponic nutrient and mixing one batch for the whole crop.
7. Check and Adjust pH
   The range to aim for, how to test it and how to adjust it.
8. Set Up and Transplant
   Filling to the right level and moving the seedling in.
9. Light and Location
   Window or grow light, and keeping the solution cool.
10. Weekly Checks and the Air Gap
    What to look at each week, and how to top up safely.
11. Harvest Your Kratky Plants
    When and how to harvest, and how to reset for the next crop.
12. Fix Common Kratky Problems
    Wilting, yellow leaves, root rot, algae and more.
13. Next Step: Fruiting Plants
    Tomatoes, peppers and cucumbers: bigger containers and topping up.
14. Grow Strawberries with Kratky
    Day-neutral plants, a dry crown and pollinating by hand.

How to use the course

Each lesson covers one step and ends with a short task. New here? Read Start Here first.