Mason jar hydroponic cup / net cup

Kratky Method Net Cup for Mason Jars

UPDATE 20.03.2026: Wide mouth also avaliable as print profile.

A 3D-printable net cup designed for passive hydroponic growing using the Kratky method in standard Mason jars. No pumps, no electricity, no moving parts — just water, nutrients, and sunlight.

What is the Kratky Method? The Kratky method is the simplest form of hydroponics. A plant sits in a net cup with its roots reaching down into a nutrient solution. As the plant drinks, the water level drops, exposing part of the roots to air. This air gap provides oxygen to the roots while the submerged portion continues to absorb nutrients. No water changes or circulation needed — just set it and let it grow.

How to Use:

1. Print the net cup in your preferred material (PETG recommended for water resistance, PLA works fine for short-term use).
2. Place a small piece of rockwool, sponge, or coco coir in the center to hold your seed or seedling.
3. Fill around it with hydroton (clay pebbles), perlite, or similar growing medium.
4. Fill your Mason jar with water and hydroponic nutrient solution (follow your nutrient brand's instructions).
5. Set the net cup into the jar so the bottom just touches the water surface.
6. Place in a sunny windowsill or under a grow light.
7. Watch it grow! Top off nutrients only if needed — most leafy greens will grow to harvest without any maintenance.

Best Plants for Mason Jar Kratky: Lettuce, basil, cilantro, mint, green onions, spinach, and other small herbs and leafy greens.

Print Settings:

• Material: PETG (preferred) or PLA
• Layer height: 0.2mm
• Infill: 15–20%
• Supports: None needed
• Tip: Ensure the mesh/slot openings print cleanly so roots can grow through easily.