NOGALES, Ariz. — Protected agriculture in Mexico is on a roll.

Approximately 37,000 acres of fruits, vegetables and other items are being grown in shade houses or greenhouses in 2010, according to the U.S. Department of Agriculture’s Foreign Agricultural Service. That’s up from 18,500 acres in 1999, and a 40% increase over the past three years.

This upward trend should continue for the next several years, especially for tomatoes, bell peppers and cucumbers, according to FAS.

Just over half of that acreage is dedicated to products grown for export to the U.S., said Eric Viranonces, chief executive officer of AMHPAC, an organization based in Culiacan, Sinaloa, that represents growers of protected agriculture throughout Mexico.

Viranonces expects protected agriculture destined for the U.S. to grow about 10% this year.

“Protected agriculture in Mexico is huge,” said Jaime Chamberlain, president of J-C Distributing Inc.

Thanks to protected agriculture, some commodities are available out of Mexico year-round, he said.

J-C Distributing has been converting its vine-ripe tomatoes to protected agriculture over the past six years, he said. And this year, a large portion of its grape tomatoes are being grown in shade houses for the first time.

The largest growers for Ciruli Bros. LLC in Rio Rico increased their protected acreage by 30% last year, said partner Chris Ciruli.

Three years ago, half of the company’s acreage in Culiacan was protected. That figure now has risen to 90%.

“The trend is going to continue to go higher,” Ciruli said.

All of the bell peppers from Del Campo Supreme Inc. are grown under shade cloth, said Jim Cathey, general manager. And the company plans to grow more roma tomatoes in shade houses, increasing a little bit at a time.

The company moves slowly when transitioning from open-field to protected agriculture, even though the firm has been doing it for 12 years.

“You have to know how to grow (in shade houses),” Cathey said. “It’s a different type of farming.”

Del Campo Supreme took three years to put all of its bell peppers under shade cloth.

Farmer’s Best International LLC in Rio Rico has 1,300 acres of protected cucumbers, bell peppers, round tomatoes and roma tomatoes, up slightly from last year, said Steve Yubeta, vice president of sales.

Shade houses and greenhouses offer many advantages for growers.

For one thing, they can lengthen the season, allowing growers to produce fruits or vegetables earlier or later in the year than with field-grown product, said Lance Jungmeyer, president of the Fresh Produce Association of the Americas.

“There’s a higher assurance level that you’ll have the product available,” Chamberlain added.

Yields under protected agriculture can range from two to five times what they are under field-grown conditions, said Martin Ley, vice president at Del Campo Supreme.

Growers actually can get greater volume from less acreage with protected agriculture, he said.

The type of protected agriculture a grower uses depends on climate and commodity.

For example, in northern Mexico, where winter are cold and summers are hot, glass greenhouses work best, said Ricardo Crisantes, general manager at Wholesum Family Farms.

In central Mexico, heated plastic structures that are more sophisticated than shade houses but not as technologically advanced as glass greenhouses tend to work best, he said.

In Culiacan, with mild winters and humid conditions, shade houses seem to do the job.

Protected agriculture is more expensive than growing in open fields, but it’s worth the cost, growers said.

“The initial cost is much higher to put your product in protected agriculture, but over the long haul, using less pesticide will save you money,” Ciruli said. “There are definitely some pluses to it.”