What do you do with an extra 42U server cabinet? One engineer turned it into a hydroponic garden. Starting in early 2026, they began growing lettuce in a spare rack cabinet after ending up with two whole cabinets when only 10U was needed.

The flood and drain system uses rockwool and clay balls as growth medium, with nutrient-rich water pumped from a 72-liter reservoir to 38-liter grow trays. The setup includes rack-mount shelves, LED grow lights, and a submersible pump controlled by cron jobs through an old PDU.

Despite warnings from online forums that flood and drain systems are terrible for growing anything but mold, the project succeeded beyond expectations. The engineer grew multiple lettuce varieties and herbs, though basil seeds never sprouted. The system leaked only twice and produced edible salads. The creator emphasizes this isn't a serious guide - there are better approaches for actual food production - but it proved a fun way to learn about hydroponics while repurposing unused equipment.