Importance of Greenhouse site Selection and Construction
And of course, you want your greenhouse site to have either excellent soil quality or the potential to become so. If the area is already cultivated and the soil is healthy, Biernbaum says, little preparation is required.
“To solve our flooding problem, we installed four inch drain lines around each house,” Biernbaum explains. “The lines are covered with crushed gravel and have eliminated flooding while also deterring tunneling rodents and preventing grass from growing into the houses. Whaddya know. Solutions to two challenges I never knew might exist.” Now with the addition of 4-inch drain lines around each structure, the greenhouses at Michigan State University’s Student Organic Farm no longer flood during spring thaw, but instead grow a plentiful harvest.
Regulations - Greenhouse operations can only be located in certain zones. Frontage, side yard distances, signs and the number of parking spaces are frequently specified. A check with the zoning enforcement officer should be one of
Planning for a new greenhouse is one of the most important steps a grower will have to take. Proper site selection and location with relation to markets, labor, utilities and future expansion make the difference in how profitable the business becomes.
It is best to build your greenhouse on elevated ground so runoff flows away from the structure, Biernbaum advises. Don’t forget about the extra water coming off the roof either, he says, especially if you have heavier soil.
During the first year of CSA, 40 percent of the Student Organic Farm’s crop came from the greenhouses, which were only 20 percent of the farm’s first-year production area. Greenhouse production has proven an important asset, and it is for that reason that we are all seated before Bierbaum to learn about year-round greenhouse production.
“You can’t be afraid to expose yourself to new ideas,” John Biernbaum tells us whimsically as he presents a photograph of the rear view of a barelegged man holding open his trench coat to a facing sign reading “New Ideas.” Thus begins a fun-filled day at Organic University, the pre-conference program to the 2005 Upper Midwest Organic Farming Conference.
Supplemental Lighting - To overcome variable weather conditions and still meet a production schedule, supplemental lighting may be needed, especially in the propagation area and nursery. High pressure sodium (HPS) fixtures are the most efficient and should be installed to provide at least 900 foot-candles at plant height.
“If the site is in sod or pasture and has not been cultivated, it is particularly important to start in advance so the sod has time to break down,” Biernbaum tells the class. “Plowing or tilling is one way to break the sod, although sheet composting without cultivation is also an option. Regular cultivation and irrigation will help reduce the weed seed bank, and additions of organic matter from green manure or compost helps build soil organic matter and nutrient availability.”
Energy Conservation - With the high cost of fuel, installation of energy conservation measures are important to reduce production costs. Double glazing, perimeter insulation, energy/shade screens and wind breaks should be considered. Management practices, such as growing crops that require cooler temperature, purchasing plugs or prestarted plants, keeping the growing space full and the use of supplemental carbon dioxide can also help.
Take trees, mountains, and other obstructions that could possibly cast a shadow on the greenhouse into consideration, especially in the morning. Mountains also have the ability to affect wind and storm patterns. Other environmental considerations include: clouds and fog, which can gather at certain
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