Backed by consumer demand for fresh tomatoes year round, the indoor acreage devoted to growing tomatoes has become nearly six times as large since the early 1990s, said Roberta Cook, a marketing economist who helped write what many in the industry consider to be the definitive report on greenhouse tomatoes in 2005.

Those tough pink ones are still good and cheap enough for most fast food restaurants and the food service industry, which buy about half the fresh tomatoes sold in the United States. But with shoppers willing to pay a premium  even $4 to $5 a pound  for red vine-ripened ones with more flavor, greenhouse tomatoes now represent more than half of every dollar spent on fresh tomatoes in American supermarkets, according to figures from the Perishables Group, a market research firm in Chicago.

“In the U.S., it’s hard to be competitive without a 20-acre minimum block,” Ms. Cook said.

The plants here at Backyard Farms number about 550,000. Each consists of two plants  the vines of new varieties, constantly tweaked for flavor, color, freshness and myriad other traits; and the roots of another, grafted together at a thickly scarred “V” near the base.

One half grows down into a sterile dirt-substitute made from fibers spun out of volcanic basalt, absorbing a custom hydroponic cocktail mixed by Mr. de Kok. The other half stretches toward the glass ceiling, growing a foot every week along a nine-foot length of twine. When the plants reach the top, workers reel more twine from the spool, shift the entire row horizontally and band each vine to its neighbor so that by the end of a plant’s life it might grow parallel to the concrete floor for as many as 20 or 30 feet, a dozen vines tangled together like garden hoses, before each makes its own graceful turn upward.

“It’s like a bonsai tree  you have to treat every plant exactly the same,” Mr. de Kok said. “As soon as it gets uneven, that’s when it starts to get away from you.”