Biodynamics Greenhouses are designed for the specific purpose of growing high quality specialty crops using controlled environmental agriculture (CEA) techniques and the latest technology in Hydroponic Growing Systems. The populariy of growing hydroponically is in response to a tremendous existing consumer market need for high-quality, locally-grown produce that can’t be met by field growers.
Hydroponics is the science of growing plants in soilless, inert media to which is added a water soluble nutrient containing all the essential elements needed by the plant for optimum growth and development. The term “hydroponics” was derived from two Greek words, “hydro,” meaning water, and “ponos,” meaning labor. In the past, there have been many types of hydroponic systems, some of which have failed while others have met with varying degrees of success. Growing media used have included sand, gravel, peat moss, rice hulls, cottonseed hulls and vermiculite. Most, if not all, of these systems no longer find acceptance in the industry due to the inherent problems associated with each one.
Researching plant nutrition and physiology dates back to the early 1600s, however, plants were grown by soilless methods far earlier. The Aztecs of Mexico devised a system of floating gardens to utilize a non-arable swamp land. The famous hanging gardens of Babylon are another example of hydroponic culture. Egyptian hieroglyphic records dating back to several hundred years B.C. describe the growing of plants in water.
Hydroponics Greenhouse Technology
Some estimates put the number of hydroponic greenhouses in the U.S. at 65,000, and the number of hobby greenhouses in the U.S. at three million and growing, according to Hobby Greenhouse.
The greenhouse industry of North America is probably one of the most difficult segments of agriculture to categorize into typical size and production units. The industry is diverse in crops and quality of crops grown and growers are extremely individualistic in marketing strategies.
The commercial greenhouse growers market is divided between food/vegetable growers and flower growers (floriculture). Greenhouse food crops grown commercially include tomatoes, peppers, lettuce, cucumbers, eggplant and a variety of other edibles.
Numerous differences in local climates and costs of resources affect the national greenhouse industry. Within Ohio, one can find large areas of unheated-single-layer-polyethylene greenhouses for "over wintering" nursery crops as well as a unique 1,200 ft. growth chamber with gas-engine-generators and HID lamps for growing lettuce.
All U.S. greenhouse growers are faced throughout the year with uncontrolled and aggressive competition from imported vegetables. There are very few import barriers and the U.S. interstate highway and air transport systems are very efficient. For example, more than 95 percent of the winter vegetables such as tomatoes are field grown in Florida, Mexico, and California to be shipped to the populace in the northeastern U.S. The field grown tomatoes are typically low priced and have good external (appearance) quality, even though the internal quality will usually be inferior to the greenhouse tomato. This greenhouse quality advantage has been highly profitable for small growers selling an identified tomato in local markets, but has proven to be of slight advantage for large growers selling unidentified tomatoes in mass markets.
The rapidly growing greenhouse tomato industry has become an important part of the North American fresh tomato industry. Greenhouse tomatoes—grown in fixed structures as opposed to open fields or temporary structures—now represent an estimated 17 percent of U.S. fresh tomato supply, according to “Greenhouse Tomatoes Change the Dynamics of the North American Fresh Tomato Industry,” by Roberta Cook and Linda Calvin, USDA/ERS, April 2005.
Even though greenhouse tomatoes still constitute a minority share of the U.S. fresh tomato market, their influence is concentrated and growing in retail channels, which represent about half of U.S. tomato consumption. Around 37 percent of all fresh tomatoes sold in U.S. retail stores are now greenhouse, compared with negligible amounts in the early 1990s.
In the modern era, it wasn’t until the early 1930s that researchers began to realize the agricultural potential of hydroponics. W.F. Gericke of the University of California, who coined the term “hydroponics,” grew vegetables, grain crops, ornamentals, and flowers using water culture.
Gericke’s application of hydroponics soon proved its viability by providing food for troops stationed on non-arable islands in the Pacific in the early 1940s. In 1945, the U.S. Air Force solved its problem of providing its personnel with fresh vegetables by practicing hydroponics on the rocky islands normally incapable of producing such crops.
By the 1970s, traditional farmers and eager hobbyists began to be attracted to the virtues of hydroponic growing. A few of the positive aspects of hydroponics include:
- The ability to produce higher yields than possible from traditional, soil-based agriculture.
- Allowing food to be grown and consumed in areas of the world that cannot support crops in the soil.
- Eliminating the need for pesticide use (considering most pests live in the soil), effectively making air, water, soil and food cleaner.
In the mid-1980s, hydroponics took a major step forward with the introduction of two superior growing media—rockwool and perlite, which have allowed the science of hydroponics to move forward and become accepted as a practical and profitable way of growing crops.
Today, computerized environmental control systems, automated injector feed systems, plastic plumbing and grow bags, and other technological innovations have allowed growers to become increasingly efficient in their production of crops using hydroponics, thereby reducing both capital requirements and operational costs.
NFT (Nutrient Film Technique) System
In this continuous 24-hour operating system, plants are suspended with their roots being bathed in a thin film of nutrient solution. Recently, NFT systems have become recognized as the single best way to grow “fancy” lettuces and other leaf crops, including herbs.
A buoyant raft drilled to hold plants is floated on the nutrient solution. The plant roots grow down into the media. This approach adds considerable weight, depending on the depth of the hydroponic tanks, so it is most commonly used in ground-mounted greenhouses, not rooftop applications.
This system consists of two containers. The lower container holds the nutrient solution, while the upper container holds the plant in a medium. Holes drilled in the top container allow the nutrient solution to reach the medium and plant roots.
Deep Pot System
A bucket lid with a growing pot built in is filled with medium and placed on a bucket filled with nutrient solution. Again, the nutrient goes through the perforations in the growing pot to feed the plant.
Ebb & Flow (Fill and Drain) System
During World War II, the U.S. broughT hydroponics to the world with this updated method. A bed filled with no-floatable medium is alternately filled and drained of nutrient.
Containers or troughs are filled with a medium containing plants. Plants are fed nutrient solution on a timed sequence.
The plants are suspended in the air and their roots are misted with nutrient solution on a timed sequence.