Hydroponic Hurrah:
Popularity is growing for produce grown without soil

The following is excerpted from an article by Bob Johnson appearing in "The Grower,' June-July 1999.

The hydroponic revolution that until a few years ago was confined to Europe, Canada, and Australia has reached the United States. After a decade of double-digit growth, U. S. hydroponic vegetable production has approached the 1,000-acre mark. With tomatoes leading the way, followed by bell peppers and cucumbers, the United States has surpassed Canada in hydroponic vegetable production, and industry insiders think the boom has just begun.

Large enterprises have discovered the mainstream U. S. Market. Nearly one-fourth of all the hydroponic vegetables in the United States are grown by two firms Colorado Greenhouses, Fort Lupton, Colorado, and Village Farms, which has greenhouse operations in Virginia, Texas, New York, and Pennsylvania. The largest hydroponic grower in Canada, Houweling Nurseries, Delta, British Columbia, recently has set up operations in Southern California.

"Some companies were growing 25 percent a year, and to the best of my knowledge are continuing to grow," said Pedro Sole, vice president for quality assurance and research and development, Colorado Greenhouses. "It will continue as long as the consumer is willing to pay the extra price for the quality of hydroponic tomatoes." Dave Walker, western regional manager for Agro Dynamics, Ventura, California, a sister company of Village Farms, said, "There are 1,000 acres of vegetables under glass in this country right now. We feel at 7,000 acres we will be approaching the saturation point."

Encroaching Entries.
The fast-growing hydroponic industry already has begun taking bites out of the market for field-grown fresh-market tomatoes. The imported hydroponic-tomato markets are growing, and are expected to continue to grow. It is difficult to tell precisely how much the hydroponics have cut into the market for field-grown tomatoes, because the greenhouse sector has taken off at the same time as growers in both Florida and California have found themselves besieged by tomatoes from Mexico in the post-NAFTA era.

The hydroponic revolution began in the Netherlands, inspired largely by the importance of reducing reliance on methyl bromide. Until the 1980s, 70 percent of all the methyl bromide used in the Netherlands was used to fumigate the soil for tomato cultivation. That use has been entirely eliminated in the Netherlands, however, largely because most tomatoes are now grown hydroponically.

Growers Face Challenges Without Soil.
The hydroponic grower must take care to monitor and control the growing process vigilantly. "The biggest mistake I see in the growing process is a lack of investment in environmental controls," Dave Walker said. He cited in particular the need to invest adequately in equipment that will monitor and control the humidity, temperature, venting, and light. "It [hydroponics] requires much tighter control than cut flowers or bedding plants," he said. "And it all translates into kilos per meter. Other than that, hydroponics is a lot more forgiving than people think."

Besides controlling the greenhouse environment, it is essential to monitor and control the irrigating solution. And nothing is more important than maintaining a properly acidic solution. "Incorrect pH is the biggest problem with the solution. If the pH is too low, you burn the roots, and if it is too high, the plant turns yellow because the roots can't absorb manganese," said a commercial hydroponic grower, who suggested a pH of 6.0 for tomatoes. Maintaining a proper pH requires constant adjustment. Commercial growers check and adjust the pH of the solution by hand everyday, while the control system automatically monitors the control system every second.

Once the proper pH has been determined, it is necessary to determine the changing nutrient needs of the crop as it matures. In general, early on, the plants need a solution rich in nitrogen and calcium. Later, fruiting plants such as tomatoes need a solution rich in potassium to feed the fruit.

When a problem develops in the solution, the medium can be flushed out. Or it can be discarded and replaced, once the proper balance in the nutrient solution has been established. Besides restoring the proper nutrient balance, this solution is a key advantage hydroponic growers have over greenhouse soil growers when it comes to eliminating a disease-infested growing medium.

Research on the best growing medium for hydroponic vegetables currently is being conducted in Europe and by the leading companies in North America. But rockwool still is the medium of choice for vegetables.

Numerous books on hydroponics, which include recommended pH and nutrient solution-requirements, have been written recently. However, the literature tends to trail behind the latest technologies in this fast-changing field. Byron Smith, president of Sunizona, Pearse, Arizona, which grows cucumbers hydroponically, thinks the best source of current information on the environmental and nutrient needs of the major crops, as well as the newest technologies, can be found in the "Greenhouse Vegetable Guide," which is available through the Ministry of Agriculture in British Columbia (604) 633-4211.

This article appeared in the January 2000 issue of Vegetable Production and Marketing News, edited by Frank J. Dainello, Ph.D., and produced by Extension Horticulture, Texas Agricultural Extension Service, The Texas A&M University System, College Station, Texas.

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