Kratky Cilantro Container: What Size and Type to Use
The Kratky method is simple, so the container does most of the work. A good Kratky cilantro container holds the nutrient solution, keeps light out, and supports the plant. The step-by-step Kratky method guide for cilantro calls for "a suitable container" that is clean and free from contaminants. This post explains what that means in practice.
What the container has to do
- Hold enough solution. There is no pump in a Kratky system, so the plant drinks from one fill. More volume means a slower drop in the water level.
- Block light. Light reaching the nutrient solution encourages algae. An opaque container, or one wrapped in something dark, avoids the problem.
- Hold the plant. Whether you use a floating medium, as the guide describes, or a net pot in a lid, the container has to support the plant and let the roots grow down into the solution.
- Be easy to clean. Start with a clean container every time, and rinse it between plantings.
Size
Cilantro roots grow downward, so choose a container deep enough that they are not hitting the bottom early. Beyond that, bigger is more forgiving, because a larger volume of solution changes more slowly. How many plants you put in a container matters too: the more plants sharing one fill, the faster the level falls.
If space is tight, Calypso Cilantro is described on our cilantro varieties page as compact and requiring minimal space, which makes it a good match for small indoor containers.
Material
Food-safe plastic, glass and ceramic are all common. Avoid bare metal, which can corrode in contact with nutrient solution. Glass jars work, but they let light through, so wrap them or use an opaque sleeve.
Why a Kratky container is not topped up constantly
As the plant drinks, the water level drops and leaves an air gap above the solution. The upper roots sit in humid air, and that is where they get their oxygen. The lower roots stay in the solution and take up water and nutrients. That air gap is the reason the method works without an air pump.
Even so, the guide advises checking the water level regularly and topping up as necessary, so the roots stay in the solution. If the level drops low before harvest time, add a little and check the pH afterward, as covered in hydroponic cilantro nutrients: what to mix.
A simple checklist
- Clean container, deep enough for the roots
- Opaque, or covered to block light
- Lid or floating medium that holds the seeds or seedlings in place
- Room for each plant, without crowding
Once the container is ready, start your cilantro from seed.
Cleaning between plantings
When a crop is finished, empty the container and wash it with warm water and a little mild soap, then rinse it well so no residue is left. Scrub away any slime or algae. A clean container gives roots the best start and stops problems from carrying over to the next planting.
Common questions
Can I use a mason jar?
Yes, for a small setup, as long as it is clean and the light is blocked. Glass lets light through, so wrap it or use an opaque sleeve. A small jar holds little solution, so the level will drop faster.
How many cilantro plants can share one container?
That depends on the container size. The guide says to place seeds evenly spaced, with access to light. Fewer plants per container means the solution lasts longer and each plant gets more room.
Does the container need a lid?
A lid or cover helps keep light out and keeps dust and debris out of the solution. Cut an opening for the plant or the floating medium.