Build a simple Kratky jar for herbs or leafy greens with guidance on container choice, light blocking, nutrients, net pots and the root air gap.
What you need
You need an opaque or light-blocked jar, a net pot or secure plant support, inert growing medium, a seedling and a complete hydroponic nutrient mixed according to its label. A larger container is more forgiving than a very small jar.
Step-by-step setup
Mix nutrient solution, fill the container high enough for the young roots or moist medium to access solution, fit the plant securely, then place it where it receives suitable light. As roots develop and water is used, allow an air gap to form.
Block light from the reservoir
Light entering nutrient solution encourages algae. Wrap or cover clear jars so the reservoir stays dark while leaving the plant exposed to light.
Maintenance
Watch root colour and smell, plant growth, reservoir temperature and remaining solution. Avoid unnecessary daily adjustments; investigate a visible problem before changing several variables at once.
FAQ
Does Kratky need an air pump?
No. A conventional Kratky setup is passive and relies on the air space above the nutrient solution. If you add continuous aeration, the system is operating more like DWC.
Should I keep topping up the reservoir?
It depends on crop duration and container size. For longer crops, topping up may be needed, but preserve an air gap around the upper roots rather than restoring the original full level.
