Choosing the right structure

April 2, 2002 - 12:41

Factors and trends to keep in mind for those on the grow.

Whether you’re a small, medium or large grower, it is important to remember the basics when choosing a structure for your situation. So, let’s review the fundamentals.

Greenhouse Structures 101

Type of Crop. If you
are hardening your crop, you might want a structure with a retractable roof so
you won’t have to move the crop and can save time and labor. If you are a
plug grower or are germinating plants, you might want your structure completely
closed off from the elements so you can control the ventilation, humidity,
heating, cooling and sunlight.

Location. A grower in Florida will not have the same
structural needs as one in Michigan because of climatic differences, including
the amount of sunlight received. Paul Thomas, associate professor of
floriculture at the University of Georgia, recommends checking with the
National Weather Service to determine the worst conditions on both the cold and
hot sides. “By over-engineering, we’re engineering for the
worst-case scenario, not the average,” he says. For instance, you may
want to ask, “What was the coldest/hottest night’s temperature in
the last 100 years?”

Cost. The price of a
greenhouse structure is measured by the square foot and varies by location.
Once you have determined the price per square foot, multiply it by the square
footage you require to arrive at the cost of the structure. style="mso-spacerun: yes"> 

Land. When purchasing land on which to build a structure, consider
zoning laws. Research the area before purchasing the land — which should
be zoned for business, not residential use.

Water restrictions and water quality are also something to
research. Property might be ideally situated to the highway with appropriate
windbreaks and plenty of room for expansion, but if the water quality is poor
enough, none of this matters

Square Footage.
Don’t simply plan for now, but for any future expansion, including
technology; the more you prepare for contingencies, the less surprised you will
be when they are needed.  

Structure Types.
Quonset huts (cold frames or hoop houses) are generally less expensive and are
most often used by growers who do not necessarily require the more expensive
glass or poly-covered structures. Open-roof houses have sections that move in
and out, while retractable-roof houses have a roof that literally retracts. The
result is the same for each: Growers can harden their crop by exposing them to
the elements, taking advantage of both natural sunlight and ventilation. Venlo
houses also expose crops to the outside air since they are vented. Any of these
houses can be gutter-connected, a less-expensive option that allows you to
incorporate the same heating and cooling systems and makes moving plants from
one house to another easier.

Current trends

Many of the structure experts GPN talked to noted several
current trends in the structure industry: turnkey houses, retractable-roof
houses and upgrades in technology and automation. 

One type of turnkey solution involves the grower selecting
the structure, heating and cooling systems and other equipment, while someone
else does all the work — from pouring the foundation to installing the

The other type of turnkey structure may involve hiring a company
to erect the grower’s structure as well as install heating and cooling
systems, but they may contract with another company to pour the foundation.
Growers have more control over the companies they contract with and more
selection in their heating, cooling and irrigation systems with this type of

The second trend that experts have observed is upgrades in
technology. As Thomas notes, “I would recommend that even the beginners
who are putting up Quonset huts look at labor-saving features as part of their
initial investment — automatic watering systems, computer-controlled
environments. The only way to make a profit is to save on your labor
costs.” In the aftermath of the fuel crisis last year, growers have to be
vigilant about their initial choices as well as their upgrades.

About The Author

Elizabeth Pensgard and Carrie Burns are associate editors at GPN magazine.

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