Single-Seedling Propagator for Standard Canning Jar

A compact 3D-printed base that turns a standard glass jar (70mm inner neck diameter) into a perfect greenhouse for germinating a single seed or rooting a cutting. The transparent glass creates an ideal microclimate with high humidity, while the built-in ventilation system allows you to easily control the airflow without removing the jar.

Key Features & Benefits

• Precise Fit: The central recess is specifically designed to hold standard peat pellets.

• Adjustable Ventilation: The side wall features a perforated section that can be opened or closed using a removable sliding plate.

• Air-tight When Closed: With the slide inserted, the jar fits tightly against the base, effectively retaining moisture inside.

• Space-Saving & Mess-Free: Takes up minimal space on a windowsill and prevents water spills.

• Material Recommendation: Perfectly suited for printing in PETG.

What You'll Need (In addition to the 3D printed parts):

• Glass Jar: Any jar with a 70 mm inner neck diameter (e.g., standard preserving jars for twist-off or metal canning lids). Please verify your jar size before printing!

• Peat Pellet (standard size).

• Seeds or a cutting for rooting.

3D Printing Settings

• Material: PETG is highly recommended. It is heat-resistant and non-hygroscopic, which is crucial when constantly exposed to moisture inside the greenhouse. PLA may warp over time due to heat or absorb water and swell.

• Supports: Not required (the model has no overhangs).

• Infill: 15–20% (sufficient for mechanical strength).

• Layer Height: 0.2 mm.

• Tolerance Tip: The sliding vent is printed as a separate part. If it fits too tightly after printing, gently sand the edges with fine-grit sandpaper or a file. It should move with slight resistance to hold its position.

Assembly & Instructions

1. Place the printed base on a flat surface.

2. Insert a dry peat pellet into the central recess and add water according to the pellet's instructions until fully expanded.

3. Plant the seed or place the cutting into the pellet.

4. Cover the setup with the glass jar. The jar should fit snugly onto the base.

5. Ventilation: To ventilate the greenhouse, simply insert the sliding plate into the vertical slots on the base wall and slide it to the side – the perforated holes will open. To seal it completely, slide the plate back to cover the holes.

Important Tips

• Watch for condensation: The base is air-tight. After the seedling emerges, it's crucial to open the vent daily to provide fresh air. If it stays constantly foggy inside, the seedling may develop "damping off" or mold.

• Hardening off: Once the seedling has 2–3 true leaves, remove the jar completely to let the plant acclimatize to room air before transplanting.