October 11, 2013
Purchasing A Greenhouse: Advice From The National Greenhouse Manufacturers Association
There are some common questions growers ask about structures. NGMA collected answers to the most frequently asked questions.
October 4, 2013
Top 10 Mistakes Greenhouse Growers Make When Planning An Expansion
From financing to production concerns, don't make these mistakes when planning additional greenhouse space.
September 13, 2013
Comparing LED Lighting To High-Pressure Sodium Lamps
Cuttings of vegetatively propagated bedding plants are frequently rooted in late winter and early spring to meet the spring and early summer market demand for flowering bedding plants. However, this is also the time when dirty and old glazing material, interior superstructures, and hanging baskets suspended above benches reduce already seasonally low ambient outdoor daily light integrals (DLIs) inside the greenhouse. Increasing the DLI during propagation has been shown to improve growth and quality of rooted cuttings, as well as reduce time to flower after transplanting. While maintaining clean glazing material, minimizing superstructure and reducing the density of hanging baskets may increase greenhouse DLI, the only way to appreciably increase DLI is to provide supplemental or photosynthetic lighting. Light-emitting diodes (LEDs) are solid-state, semi-conducting diodes that can emit light from ~250 nm to ≥1000 nm. There are several features of LEDs that make them attractive alternatives to high-pressure sodium (HPS) […]
August 23, 2013
Structural Design Manual From National Greenhouse Manufacturing Association Offers Construction Guidance
The manual guides designers through the building code provisions for production and commercial greenhouse structures. It includes the provisions for roof live load, snow load, wind loads and seismic and collateral loads as contained in the building code or reference standards. Structural design methods for roof framing systems, the support columns and the lateral bracing systems are also detailed. This chapter looks at bracing, connection materials, roof support systems, trusses, arches, rigid frames, gutters, ridges, purlins and more. It also includes two design examples. Click here to visit the NGMA Downloads page and click on the dropdown menu under Design Manuals.
August 15, 2013
Time to Upgrade Your Greenhouse Operation?
Unhappy plants, discontented workers and high production costs are all signs that it might be time for some changes to your greenhouses, says A.J. Both, associate extension specialist in the Department of Environmental Sciences at Rutgers University. “Any or all of these conditions can be a good reason to investigate and implement upgrades,” he says. Wasted Energy Energy is one of the costliest aspects of running a growing operation, second only to labor expenses. According to a fact sheet produced by Both and Michigan State University’s Erik Runkle, approximately 65 to 85 percent of the energy consumed in greenhouse production goes toward heating, while electricity and transportation make up the remainder. In older greenhouses, it’s common for air leaks to reduce efficiency, leading to higher energy costs. Both and Runkle recommend inspecting your current house’s glazing, walls, doors, fans and vents for leaks. Pay close attention to the areas around […]
July 29, 2013
Energy Conservation: Helpful Hints From NGMA
Why save energy? There are many reasons. Purchased energy is a signiﬁcant and ongoing expense for most greenhouse operations. There is high probability that energy prices will continue to rise and most greenhouse operations have the ability to economize on fuel use. Energy is consumed all the time, year after year. Once it is consumed, you can never get it back. Anytime you can save energy costs, you are moving money directly to your bottom line, increasing your margins and competitiveness. Energy-eﬃcient systems are usually engineered for optimum conversion, distribution and retention of heat. They can often produce better, more uniform crops, as well as being good for the environment. Even if it takes additional capital to achieve the highest level of energy saving, the long life of many energy-saving greenhouse system components make them sound investments. Where Can I Save Energy? • Make the most of free energy from sunlight […]
June 5, 2013
Natural Ventilation And Fog Increase Cooling Efficiency
For greenhouse ventilation, two main methods are used — mechanical and natural. Mechanical ventilation includes fan-and-pad systems, which are a type of evaporative cooling system. Fan-and-pad systems cool air by passing outside air through a wet pad, lowering the temperature and humidifying the greenhouse. This type of system works best in hotter, drier climates, because the capacity for cooling with a fan-and-pad system is very limited in humid climates. University of Arizona associate professor Murat Kacira says a drawback of using a fan-and-pad type system is that it requires a lot of energy and water. “Water is needed for the pad system, and energy is needed to run the pump for water circulation over the pad as well as the energy to run the exhaust fans,” Kacira says. “Water is a precious resource with limited availability, especially in arid and semi-arid regions. “Another issue is there can be a temperature […]
June 4, 2013
10 Snow-Related Causes Of Greenhouse Failure
John Bartok Jr., an agricultural engineer and University of Connecticut Professor Emeritus, says snow varies considerably in consistency and weight. It can be light and fluffy with a water equivalent of 12 inches equal to 1 inch of rain. Snow can also be wet and heavy with 3 to 4 inches equal to 1 inch of rain. Snow having a 1-inch rainwater equivalent loads a structure with 5.2 pounds per square foot. This amounts to about 6.5 tons on a 25- by 96-foot greenhouse. Bartok says there are several reasons for structure failures during snow storms. 1. Drifting Snow: In nor’easter storms, adjacent greenhouses or bays of gutter-connected houses that have a north-south ridge orientation tend to collect more snow on the leeward side. Snow that is lifted over the ridge of the first house can be dumped on the windward side of the second house. This creates an off-center […]
June 3, 2013
Why Greenhouse Under-Gutter Height Matters
I don’t think there are many greenhouse manufacturers still left in the Dark Ages of “keep your greenhouse low or your heat costs will rise,” but if you do come across one, run for your plant life! Here are some reasons to consider building higher. 1. Taller houses cast less shadow on your crop.I was not being facetious when I used the term the Dark Ages to describe the period of 7- to 9-foot-tall greenhouses. The modern commercial greenhouse standard height in North America is 16 feet for floral crops and 21 feet to 24 feet for vine climbing produce, but don’t quote me for too long on that one. Builders continue to raise their roofs with every build. Taller greenhouses allow you to produce more crop in the same footprint. They can accommodate double-hung and even triple-hung hanging baskets, while still providing a healthy environment for the plants at […]
May 13, 2013
Green City Growers Is Largest Urban Food Co-op In U.S.
Take a look at a unique employee-owned cooperative that grows lettuce and other greens for local food services, restaurants and grocery stores with plans to do more.