Farm Progress

To expect hundreds of thousands of acres of greenhouse farming to replace open farm ground is unreasonable, yet controlled environment production is a rapidly-growing niche market.“We’ve perfected controlled environment growing to the point where we’ve broken the sound barrier in growing vegetables in greenhouses,” says Arizona plant scientist Merle Jensen.

June 19, 2015

5 Min Read
<p>Vertical on-the-vine tomatoes growing at the University of Arizona Controlled Environment Agriculture Center in Tucson.</p>

Anticipate hungry hoards in the years to come.

In Africa, agriculture professor Gert Venter warns, “By the year 2050, predictions show 85 percent of a total world population in excess of 9 billion people will live and work in megacities, but these mighty cities have a terrible flaw different from all other cities in history - they cannot feed themselves.” 

That’s a rather scary thought when almost everything we need to increase food production becomes scarcer and more expensive every day, including land, soil, water, energy, nutrients, and a stable, reliable climate.

“This collision between huge demand - and huge scarcities - is making food the challenge of our time,” Venter said.

In fact, more than 100,000 more people will sit down to dinner than each previous day. There could be 11 billion mouths to feed by the end of this century.

Meanwhile, global food output needs to double 50 years from now to meet the demand for food for the rapidly-expanding world population.

“We will need to produce more food in the first half of this century than we did in the previous 100 centuries combined,” warns Tony Kajewski, president of the American Society of Agricultural and Biological Engineers.


Scientists at the University of Arizona’s Controlled Environment Agriculture Center in Tucson are working on an indoor solution - indoor plant production where variables can be controlled.

“We need to grow a lot more food per square meter and produce amounts we never, ever, believed we could,” says Merle Jensen, professor emeritus with the UA Plant Sciences Department and now with Greenhouse Vegetable Consultants, LLC.

As an early pioneer in the development of agricultural plastics for greenhouses, the greenhouse industry veteran has spent a lifetime bringing the concept to creation.

“We’ve perfected controlled environment growing to the point where we’ve broken the sound barrier in growing vegetables in greenhouses,” Jensen said. “We’ve made headlines by producing 100 tons of (fresh market) tomatoes per acre in three months when outside yields per year were 50-60 tons.”

Greenhouse short course

This was the theme of a recent UA short course on Greenhouse Crop Production and Engineering Design. The five-day symposium drew 75 greenhouse growers from around the globe to discuss growing crops under glass now…and in the future.

“There are thousands of acres (under glass) in production already,” said Gene Giacomelli, the CEAC’s director. 

“There’s a growth trend, maybe not towards larger (facilities), but more of these facilities,” Giacomelli said. “We have 500 acres cultivated now in Arizona and a similar number in California where field production is still the bread and butter but the transition is occurring.”

He acknowledges that conventional agriculture will continue as a mainstay of food and fiber production and all of the amber waves of grain will not fit inside a greenhouse anytime soon.

To expect hundreds of thousands of acres of greenhouse farming to replace open farm ground is unreasonable, Giacomelli admits, yet controlled environment production is a rapidly-growing niche market.

Greenhouses on Mars?

In fact, highly-controlled greenhouse production is underway at the South Pole in Antarctica and perhaps someday will take place on the surface of the Moon or Mars, he says. If this perhaps sounds unrealistic, he says all farm field and greenhouse practices are similar.

“High-volume staple crops like wheat, rice, and corn that form the basis of much of the world’s diet, are not suitable for controlled environment agriculture,” Giacomelli admits. “But CEA can complement - not replace - field crop production by extending the growing season and ensuring product quality.”

Roman emperor first?

Historically, the earliest food production in greenhouses was believed to be the cultivation of off-season cucumbers for Roman Emperor Tiberius ‘under transparent stone.’  The technology took a while to catch on until the 1600s when crops were protected against cold weather using glass lanterns, bell jars, cold frames, and hot beds covered with glass.

Today, CEA is defined as the “production of vegetables, plants, and flowers inside structures like greenhouses - high value crops at maximum productivity.”

Speaking at a previous CEAC short course, Dickson Despommier, author of The Vertical Farm: Feeding the World in the 21st Century, told attendees, “Food crises over the last 20 years (caused by) droughts, floods, political and civil unrest, allowed ‘urban agriculture’ to emerge from the primordial ooze of ideas.

The author added, “Today, throughout the technologically-gifted world, we have a burgeoning industry with Arizona as a hotbed of growing food indoors in the middle of the desert.”

High-quality produce

With little dissention, there is consensus is that CEA can provide efficient large-scale production of fresh produce, carving out market share with a combination of high crop yield and quality.

Giacomelli says greenhouse production buys the grower some insurance (admittedly at a cost) to protect crops from heavy rain, plus wind or hail storms. It helps produce food with good nutrition, sunlight, and excellent taste.

Giacomelli comes from a farm background and understands conventional agriculture, yet says more plants per unit acre per year can be grown with CEA. 

“In a lettuce field, you harvest one head at a time with stoop labor, weather permitting, while on a ‘floating raft’ one person can harvest 50 heads at a time,” he said.

Jensen discussed vertical farming projects underway in Japan where tiers of food production shelves are stacked 30-40 feet high.

“We can do this,” Jensen said, “but can we do it economically? Going higher is a dream that may happen one day, but not until we don’t have any more land in Salinas (Calif.).”

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