Grow more in less space — a 6-cell modular seed starting tray designed for deep-rooted, healthy seedlings and seamless integration with the LGP Self-Watering Tray.

The LGP 2×3 Cells XL HalfTray is a fully 3D printed plug tray holding six 80mm deep growing cells in a compact 2×3 grid. It fits exactly half of the LGP Self-Watering Tray, pairs with any other LGP HalfTray, and can also be used completely standalone — on a windowsill, under a grow light, or anywhere you start seeds.

Each cell is engineered for strong seedling development from the start — root-guiding ribs direct roots downward to prevent circling, drainage holes in the ejectors support even moisture flow from bottom watering, and the 2-stage wicking system draws water up from the reservoir below with more or less wicking depending on water level. When it's time to transplant, the plug ejectors push the entire soil plug upward cleanly without disturbing the root system.

A shared humidity dome sits across all six cells, trapping warmth and moisture to create an ideal microclimate for germination. Integrated micro-vents allow controlled airflow while maintaining the high humidity your seedlings need in early growth.

Growing Guide I've documented what I've learned while designing and using the Logical Grow Platform in a growing guide series on LogicalPlanet.com, covering everything from seeds through harvest. https://www.logicalplanet.com/collections/lgp/

How It Works

The 2×3 XL HalfTray is built around three integrated components that work together through every stage of early plant growth.

Plug Cells — Six individual growing chambers that hold potting mix and seeds. Root-guiding ribs direct roots downward for strong, compact seedlings and reduce circling before transplant.

Plug Ejectors — Removable base inserts that sit beneath each cell. When it's time to transplant, they push the entire soil plug upward for clean, damage-free removal. Drainage holes in the ejectors prevent waterlogging while supporting even moisture flow from bottom watering.

Humidity Dome — A shared translucent lid that covers all six cells simultaneously, trapping warmth and moisture for an ideal germination microclimate. Integrated micro-vents allow controlled airflow while maintaining high humidity during early growth.

2-Stage Wicking System When used with the LGP Self-Watering Tray, the plug ejectors sit above the water reservoir and wick moisture upward through a 2-stage system. More wicking occurs at higher water levels, less as the reservoir drops — giving your seedlings consistent bottom moisture without waterlogging.

Key Features

• 6-cell plug tray in a compact 2×3 grid
• 80mm deep cells for strong root development
• Root-guiding ribs direct roots downward and reduce circling
• Drainage holes in ejectors support even moisture flow
• 2-stage wicking system for bottom watering integration
• Shared humidity dome across all six cells
• Integrated micro-vents for controlled airflow
• Plug ejectors for clean, damage-free transplanting
• Fits half the LGP Self-Watering Tray
• Compatible with all LGP HalfTray options
• 100% printed, no supports required
• Use standalone or as part of the full LGP system

Dimensions Overall: 155mm × 120mm × 110mm (with dome) Cell depth: 80mm Individual cell opening: approximately 50mm × 60mm

Perfect For

• Seed starting and early growth under any grow light
• Integration with the LGP Self-Watering Tray for hands-off bottom watering
• Growers who want more seedlings per tray with individual cell control
• Clean transplanting without disturbing root systems
• Use alongside LGP Single Cell HalfTrays for mixed growing configurations

Printing Notes

These parts are forgiving and print successfully in most common materials.

• Prints support-free in provided orientations
• PLA or ASA recommended (see notes)
• 40% infill for general use, 100% for maximum longevity
• Use translucent material for the Humidity Dome for best results
• 0.4mm nozzle, 0.2mm layer height, 4 walls, Arachne wall generator

Notes: For long-term or outdoor use, ASA is recommended. PETG works well for indoor use. PLA at 40% infill is adequate for most indoor seed starting applications.

Print with Confidence I design and test my models carefully, but if you run into what appears to be a genuine design issue — a fit problem, a tolerance that doesn't work, or something that just doesn't behave the way the instructions suggest — let me know and I'll fix it. My goal is that every design I publish works as described. Email me at logicalplanet3d@gmail.com with details and I'll sort it out.

Note: I'm not able to account for every printer and material combination, so I recommend reviewing the print settings carefully before starting. Issues arising from incorrect settings or materials are outside the scope of this, but I'm still happy to help troubleshoot.

An Evolving System — Your Feedback Matters I've been growing in the LGP system for several months now, and that real-world experience has shaped almost every design decision in this release. It's been invaluable — and it's also shown me that no amount of bench testing replaces actually growing plants in a system over time.

I consider the LGP an evolving platform, not a finished product. If something works better a different way, or you discover something I haven't thought of, I genuinely want to hear about it. Your growing experience is part of what makes this system better for everyone. Reach out on Discord or email me at logicalplanet3d@gmail.com.

Related Links Logical Grow Platform (LGP) — Main Platform https://than.gs/m/1511734

LGP Self-Watering Tray https://than.gs/m/1540081

LGP Single Cell HalfTray https://than.gs/m/1540075

LGP Single Cell ThirdTray https://than.gs/m/1540077

Deep Cell Plug Tray – 3×5 Modular Seed Starter System https://than.gs/m/1511704

Deep Cell Plug Tray – 2×5 Modular Seed Starter System https://than.gs/m/1511705

Deep Cell Plug Tray – 3×2 Modular Seed Starter System https://than.gs/m/1511706

Join the LogicalPlanet Discord https://linktr.ee/logicalplanet

Visit my blog for more details and other designs https://www.logicalplanet.com/

Revisions and Updates I occasionally update and revise my designs. When I do, I'll document the changes here. Check back periodically for the latest revision notes or if you're experiencing any issues with a model. Please email me at logicalplanet3d@gmail.com if you would like me to make a revision or have comments about this design.

2026-04-17: Initial release.