<p>They grow bright and round, first green then red, on miles of tangled vines rooted in the shredded shells of coconuts.</p><p>Every year, a massive greenhouse billed as the largest tomato hothouse on the East Coast churns out nearly 15 million pounds of tomatoes a year.</p><p>It's not the perfect location for a greenhouse. The hot and humid summer weather requires Sun Valley Farms, a Colorado-based company that is the nation's fifth largest producer of tomatoes, to close the greenhouse in late July and August just as many people's backyard tomato patches are reaching their peak.</p><p>Still, its location is no accident. The greenhouse is warmed in the winter months by excess steam from the nearby Birchwood power plant. The steam flows through metal railings on the ground that act as a radiator. The steam pipes also serve as guiderails for special carts that run along the aisles allowing pickers to reach the top plants.</p><p>And while the climate is not ideal, the location on Virginia's rural Northern Neck is otherwise perfect for tomatoes picked on a Tuesday and shipped on Wednesday to all the population centers in the mid-Atlantic.</p><p>"Will a greenhouse tomato ever be like the tomato you pick from your backyard and eat right away? No," said Dave Fahrenbruch, Sun Valley's president. "But it's the next best thing. ... You control 100 percent of what the plant is doing. You keep out the bad from Mother Nature, and let in the good, and control it."</p><p>One consequence of raising plants in such a pristine, sheltered environment is that they develop thinner skins than field-raised tomatoes. Sun Valley Farms compensates for that by packing them by hand in single-layer, lined boxes that protect the fruit during shipping.</p><p>The thinner skinned tomato yields a juicier product as well, Fahrenbruch said.</p><p>The growers at Sun Valley Farms are familiar with the opinions of some that only a traditional, field-grown tomato, harvested in August, and preferably purchased from a roadside produce stand, are worth eating. Such sentiments are especially prevalent in parts of Virginia, which is the nation's third largest tomato producer. Particularly well known in the state is the Hanover tomato, which is not a specific breed or variety of tomato but simply a tomato grown in Hanover County, north of Richmond.</p><p>"Supposedly the Hanover tomato's flavor is better because of a mineral in the soil, but that's not proven," said Colleen Calderwood, an agriculture extension agent in Hanover County. "A lot of the Hanover tomato's success is good marketing, good word of mouth."</p><p>Bob Hoffman, senior grower at Sun Valley Farms, said: "I've tasted Hanover tomatoes many times, and I'll go head to head with them."</p><p>Fahrenbruch said the company has conducted numerous taste tests, and finds little agreement among consumers about what constitutes a good tomato.</p><p>Color and freshness, on the other hand, drive a customer's decision in the supermarket produce aisle. One of the biggest trends in the tomato industry, he said, is the growth of "tomatoes on the vine," in which several small tomatoes are sold in a cluster, still attached to the vine.</p><p>Because there is no soil in the King George greenhouse _ the shredded coconut shells provide only a root base and no nutrients to the fruit _ the tomatoes are fed through plastic tubes grafted into the vine that pump a carefully concocted mix of 16 liquid nutrients and mineral salts. The solution is constantly monitored on a computer network, along with other environmental factors like temperature and humidity.</p><p>"It's as nutritious a diet as a tomato can get," Fahrenbruch said.</p>
