“We wanted to be able to offer the best product at the best price,” Mr. Rutter said, “and a big part of the cost is energy.”

As cannabis has increasingly gone legitimate — about two dozen states had already legalized it in some form before several others eased restrictions on Election Day — electric utilities have struggled to cope with the intensive energy demands of the proliferating industry.

Besides blown transformers and blackouts for utilities in some places, the ascent of Cannabis Inc. has also raised clean-air concerns in parts of the country where fossil fuels are still the main source of electric power.

Even in many places where growing marijuana is legal, cultivators are required to keep their crops out of public view. And in any case, many growers prefer having the ability to control the environment by raising the plants indoors.

Traditionally, indoor producers — formerly relegated to basements, garages and shadowy warehouses — relied on hot, high-intensity lights. When air-conditioning and ventilation were included, the energy used to grow a single marijuana plant would run seven refrigerators for the same period, according to one estimate.