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Making hydroponic vegetables work despite misconceptionsMaking hydroponic vegetables work despite misconceptions

Two common methods of hydroponic vegetable production are Nutrient Film Technique and float beds.Many growers have ventured into hydroponics because of the business opportunities, but like any form of agriculture, there is an art and science to it.

May 3, 2016

5 Min Read
<p>Greenhouse using the Nutrient Feeding Technique for hydroponic production.</p>

Commercial hydroponic production is not as common as livestock or row crop production in Alabama, but hydroponically produced leafy greens and tomatoes are extremely popular in several Alabama restaurants and dining facilities.

The term “hydroponically produced” means the produce was grown in a media such as rock wool, perlite or a nutrient solution without soil.

Joe Kemble, an Alabama Extension vegetable specialist said, “When you have soil, you can introduce more problems such as harmful pests or diseases. Soil doesn’t work in small containers because it doesn’t drain normally, and you can also introduce a lot of soilborne diseases. In this kind of system, a grower can control the environment and know what is there and how much water the plants consume or don’t consume.”

Two common methods of hydroponics are Nutrient Film Technique (NFT) and float beds.

NFT is a circulating hydroponic system that utilizes plastic channels to grow plants and works best for producing leafy greens such as lettuce or herbs and is the most desired by commercial growers. Although this option is more expensive, NTF provides a clean growing environment.

A nutrient solution flows through the channels providing plant’s roots with proper hydration and nutrients. Any nutrient that is not taken up by the plant is recirculated through the channels ensuring that all the nutrients in solution are ultimately used.

Nutrients are constantly monitored by computer systems in many commercial NFT systems. The computer will inject more fertilizer into the solution when the nutrient concentration reaches a certain level or drops suddenly.

Raft systems or float beds are another way to produce greenhouse lettuce hydroponically. In this system, foam rafts are used to float plants on a nutrient solution letting the roots grow into the solution through holes cut in the raft.

Jeremy Pickens, an Alabama Extension horticulturist, works with both floriculture and greenhouse vegetable growers and is responsible for research in the Alabama greenhouse industry.

Pickens said, “Compared to NFT systems, float beds are the less expensive choice. Even though it is less expensive, raft systems require more maintenance such as cleaning and raft replacement.”

There are several misconceptions when it comes to hydroponic vegetable production.

“I feel one of the most common misbeliefs is that hydroponics is for hobbyist and not a ‘real production system.’ The largest operation in the U.S. is over 150 acres of glass greenhouse grown tomatoes. That operation is in Arizona,” said Kemble, who is also an Auburn University professor of horticulture.

Another misconception — and possibly the greatest — is the concern that growing in a solution will negatively influence the flavor or nutrient quality compared to traditional open field production.

Pickens disagreed, “Greenhouse grown vegetables are often of higher quality and have been grown with very soft chemistry pesticides. There are a lot of growers that can get by without applying any pesticides.”

Like any production agriculture operation, hydroponic vegetable production is a seven day a week job. The greenhouses must be monitored on a daily basis. In a 30×96 foot greenhouse, sowing seeds, inspecting plants for insects and diseases, plant maintenance and harvesting consumes about 20 to 25 hours a week for most vegetable crops.

Must be able to market produce

Owner and grower of Extreme Green Hydroponics, Ralf Du Toit, distributes the majority of his crop to several dining facilities at Auburn University such as the Wellness Kitchen, Village Dining, Terrell Dining and Plains to Plate. With his operation being just outside Auburn, he is able to deliver locally every day insuring his buyers a freshly harvested crop.

“I do not harvest lettuce and keep it in the refrigerator,” Toit explained, “ Everything that is sold locally is harvested and delivered in the same day.”

Du Toit produces various types of leafy greens such as artisan and romaine lettuce, several types of tomatoes such as Beef Steak, grape and cherry, and also offers a selection of European cucumbers, basil and spinach.

Luckily for growers or someone interested in becoming a grower, greenhouse vegetable production is a growing industry in Alabama.

Pickens works as a Research Associate at the Ornamental Horticulture Research Center as a part of the Alabama Agricultural Experiment Stations in Mobile, Ala.

“We have 6 growers between Mobile and Baldwin County. There are even more scattered across the state. We will see more and more greenhouse vegetables grown in Alabama as our planet’s resources become limited. The water and nutrient-use efficiency with greenhouse grown products is much greater than open field production. You can also produce a lot more product per area than you can conventionally. I can produce five times as much lettuce per acre in a greenhouse than in a field, and I can grow 20 times the amount of cucumbers.”

Pickens said that greenhouse production is becoming more and more economically viable.

“The difficult part is marketing the product. That is the case with all produce grown in our state. Lettuce is a good example. California and Arizona produce about 95 percent of the lettuce in the U.S. They have the perfect growing environment, and when you combine that with economy of scale, they can grow lettuce at a much lower cost. With hydroponics, you need a greenhouse, and greenhouses are expensive. You also have to use energy. It is a challenge to compete with commodity priced lettuce but some growers have been able to develop markets.”

Initial start up of a greenhouse operation can be pricy. The average cost of a greenhouse is approximately $20,000 but after adding equipment for the house such as heating and cooling systems, computer monitoring systems, alarms and more, a new grower should expect to invest anywhere from $30,000–$50,000.

“Some growers have manufactured their own systems and greenhouses and saved a lot,” Pickens added.

Many growers have ventured into hydroponics because of the business opportunities, but like any form of agriculture, there is an art and science to it.

“In this case, the science or the technical side of it is not that complicated. It takes some experience to get a feel for it (the art side). If you can follow a recipe and do middle school math, you can grow hydroponic vegetables,” said Pickens.

One cannot simply begin growing vegetables and become an expert overnight. A grower must learn about each vegetable and its specific nutrient levels, pest management and watering needs.

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