Los Angeles-based Local Roots’ three farms are no ordinary farms. They’re not even outside — but inside three small shipping containers. The startup uses vertical hydroponic farming, a method where plants grow year-round with LEDs rather than natural sunlight.  Instead of soil, the seeds lie on trays with nutrient-rich water, stacked from the floor to the ceilings inside the shipping containers. The containers live inside Local Roots’ warehouse in California. Local Roots’ farms save both land and water, Director of Social Enterprise Allison Towle tells…