A solar-powered farm that fits inside a closet grows 24 plants without soil.

Cities are growing while fresh water and healthy soil are running out. Farming indoors can save resources, but existing systems usually require costly setups and regular grid power. To fix this, researchers built TOTEM, an open-source vertical farming tower that runs entirely on solar power without soil. The setup stacks different units to hold water, filter it, pump it, and house growing plants. Instead of sitting in dirt, the plant roots hang inside a chamber where they receive fine mists of water and nutrients. A tiny computer controls the watering schedule and tracks chamber temperature and water levels. When tested with basil across two harvest cycles, the tower kept plants growing steadily, distributed nutrients evenly, and ran reliably off-grid in a tiny space.

Why it matters

Most vertical farms need expensive equipment and grid electricity, making them impractical where power is unreliable or land is scarce. TOTEM runs entirely on sunlight, costs little to build from common materials, and can be copied or scaled by anyone. This matters for urban communities, schools in off-grid areas, and researchers who need a cheap testbed for soilless agriculture.

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