By Brianna M. Lane For lettuce that calls indoor farms home, the “sunlight” can be blue, pink, red or other colors. That’s because LED lights allow you to pick the spectrums of the sun that are most useful for plants, said Erik Runkle, a Michigan State University horticulture professor who specializes in indoor farm lighting. Modern farmer Elise Hanson at the 80 Acres Farm in downtown Hamilton, Ohio. Image: 80 Acres Farms Usually, lettuce is grown and exported from California’s sunny Salinas Valley, nicknamed the salad bowl. But, Midwest farmers, like farmers across the nation, are growing their own indoors with LED lights.