[...] vegetables sprout in small cubes of mineral wool placed in trays of water, with water-soluble fertilizer helping them grow. Hydroponics is a method of growing plants using water infused with mineral nutrient solutions. The operation has begun selling to local restaurants, including Kitchen Table, the Grey Plume and Boiler Room. The family also is exploring selling some of its produce at the year-round indoor farmers market Tomato Tomäto. [...] the restaurant has purchased various fresh herbs, butter lettuces and some Swiss chard. The growing method allows for a restaurant to purchase clippings from a plant or the entire thing, extending the shelf life. [...] the plants don't require pesticides because of the controlled, pest-free environment, and hydroponic systems typically use 70 to 90 percent less water than conventional gardens. [...] unlike a greenhouse, the operation faces high energy costs to keep the building's temperature just so. The idea for Peterson Greens came to Ian Peterson when he returned to Omaha after graduating from Iowa State University with a degree in plant biology. With Kristen Peterson's horticulture experience — the couple met working at Lauritzen Gardens — and Tom Peterson's background in agriculture and business, the right set of skills came together to make Peterson Greens a reality. On a recent tour of the facility, the couple had just enjoyed a sandwich of hummus and assorted greens grown in their downtown facility. Kitchen Table, a downtown Omaha restaurant that focuses on using local and seasonal ingredients, already has purchased a large batch of basil from Peterson Greens, used to make pesto for potato gnocchi served with cherry tomatoes, said Jessica Duggan, who owns the restaurant with her husband, Colin.