SPEARFISH (AP) – Belle Fourche and Spearfish school cafeterias this year served produce that was grown locally – and indoors.

The Belle Fourche School District has for two years offered hydroponically raised vegetables to students on special occasions through a partnership with the Spearfish-based business Column Greens, which the Spearfish schools began to buy from this past year.

As the business prepares to migrate to a warehouse in town, co-owner Erica Proefrock said she hopes to grow both the number of schools, hospital and hotels that it sells to as well as its yield.

“We’re looking to be serving 10 pounds a week to those larger companies. We have the technology that we can provide that,” Proefrock said.

Proefrock and co-owner Alex Hamaker currently run the indoor farm out of the basement of their home in Spearfish. As hydroponic farmers, the two rely on a water circulation system and an inventive use of space to grow chard, basil, lettuce, mint and other herbs, spices and vegetables without soil. Current customers include Dakota Seafood, the Lodge at Deadwood Casino and Rapid City Regional Hospitals, the Rapid City Journal reported.

The pair will start by planting a seedling in one of the several different growing mediums that they use, which range from woven hemp mats to ground coconut husks. After growing in containers that are stored on shelves, the seedlings are transferred to vertical, hanging towers where they can mature and eventually be harvested.

A circulating network of pipes and tubes delivers water to the plants that is treated with nutrients that they require to grow. Both nutrient levels and air temperature are carefully controlled by computer. Crops at all stages of growth are exposed to LED light that helps to sustain them for only half the day, mimicking a day and night cycle.

“Basically, to run an optimal growing environment, you have to have about a 68 to 75 degree temperature during the day,” Hamaker said last month under the neon glow of the farm’s many lights.

To conserve energy, the two will typically run their lights – simulating daytime – after the sun has set.

Produce from the farm has been served to students on several occasions as part of a monthly lunch special that both school districts offer at the same price point of a standard lunch. Justin Olson, food service director at the districts’ meal program contractor Lunchtime Solutions, said he first learned about the business through the Belle Fourche school business manager, who is a relative of Proefrock’s.

Olson said his company had already bought locally raised produce and meats for the monthly special prior to purchasing from Column Greens to support the local economy. It will continue to buy from the indoor farm this coming school year, he said, adding that he hopes to arrange student field trips to it.