The Science Behind Greenhouse Growing
A greenhouse is a structure made primarily of transparent materials for the purpose of facilitating plant growth. They range from fancy glass houses with state-of-the-art heating and lighting systems to rustic, tiny buildings featuring plastic-and-wood and construction. Commercial greenhouses fall in between these two extremes. No matter what the materials, however, the guiding principles remain the same -- to create optimal growing conditions for plants. Greenhouses date back to 30 A.D. Rome and were probably among the first man-made structures to harness the power of solar energy.
How They Work
Greenhouses work by simulating optimal growing conditions in order to extend the natural growing season of a region or to produce plants out-of-season entirely. For instance, the vegetable and flower starts available for purchase in spring usually begin their lives in greenhouses. Although greenhouses began as luxury items for the wealthy during a time in history when fresh fruits and vegetables were extremely valuable, they are now used in all parts of the world to provide relatively inexpensive food and ornamental plants for large amounts of people.
The basic principle behind greenhouse growing is trapping the heat provided by solar radiation. Heat enters the interior of the structure via the sun and remains inside, warming the soil at the lowest layer first and rising upwards. Big commercial greenhouses use fans to keep the warm air circulating as evenly as possible in order to prevent overly hot spots from creating conditions conducive to mold and other fungal disorders. Some greenhouses located in areas where summer heat soars have cooling fans installed to protect the plants from wilting and drying out.
Not all greenhouses rely solely on the power of the sun. Those situated in cold climates often depend on extraneous heating in order to coax seeds to sprout and help established plants thrive.
Consider Bedner's Farm & Greenhouse for your school's next education field trip to learn more about Greenhouses in person.