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College of Food, Agricultural, and Environmental Sciences


Future of Nursery Industry May Lie in A Greenhouse

August 19, 2002

COLUMBUS, Ohio - On the Ohio State University agricultural campus sits two new buildings that university horticulturists are banking will change the face of nursery stock production in Ohio.

With roll-up end walls and sidewalls and plastic curtains for a roof, the buildings look anything but a typical greenhouse. But the structures, known as retractable roof greenhouses, have helped nursery operations in the south, southeast and Pacific Northwest become more profitable and efficient, and has increased the industries' sustainability. Hannah Mathers is helping Ohio nursery growers to do the same.

"Retractable roof greenhouses make a lot of sense for container and nursery stock production," said Mathers, an Ohio State University nursery and landscape specialist. "It gives you the flexibility of allowing the building to be a greenhouse or an outdoor environment. Sometimes you want your material in a greenhouse and other times you don't." Construction of the buildings, one with a flat-roof and the other with a peaked-roof, began last summer with the help of a $10,000 grant from the Ohio Nursery and Landscape Association. The retractable roof greenhouses are the first of their kind to be used for nursery production in the Midwest.

The idea of natural ventilation is the driving innovation behind retractable roof greenhouses. The design allows a grower to retract up to 90 percent of the roof, guaranteeing that temperatures never rise above ambient. The ability to retract the roof and roll-up the sides allows for better temperature and humidity control and improved wind and light conditions.

Stephen Myers, chairman of Ohio State's department of horticulture and crop science, said retractable roof greenhouses would not only benefit the nursery industry, but would also be useful in other agricultural areas.

"I think the application of retractable roof greenhouses will expand into other crop industries like vegetables and fruit, as well as interfacing with pest management programs," said Meyers. "For example, hail is a problem for crops. You can just hit a button and close the roof. If birds are a problem with cherry trees, close the roof. If it's too hot, close the roof. You can really do a lot of things with it that can be to a grower's advantage." The justification of retractable roof greenhouses in Ohio is already being met with some skepticism in the nursery industry, but Mathers is looking to change public opinion by demonstrating their usefulness, efficiency and affordability through a series of research studies.

One that is generating the most attention is a project funded by a $58,000 16-month U.S. Department of Agriculture/Ohio Department of Agriculture (USDA/ODA) Specialty Crop Block grant to develop an Ohio tree liner production system. Mathers and Dan Struve, an Ohio State horticulturist, are the authors of the grant and applied with the Ohio Nursery and Landscape Association to obtain the USDA/ODA funding.

The study, which began this month, analyzes the feasibility of growing tree seedlings to "whip" height -- four to eight feet tall and a 1/2 inch to 3/4 inch in diameter -- to be sold as tree stock to other nurseries in Ohio and other parts of the nation. Currently, the Ohio nursery industry does not grow its own whips because the growing season is too short. Nurseries obtain whips from the Pacific Northwest, mainly Oregon, then grow them on a larger stock.

"Many larger nurseries in Ohio export 70 percent of what they grow in nursery stock. Ohio is well positioned geographically to increase its market. It's a shipping hub," said Mathers.

Ohio growers import approximately $14 million worth of tree liners from the West annually at an average cost of $15 per liner. It is estimated that Oregon liner sales into Ohio and surrounding states total $50 million a year.

"Ohio growers can capture that $50 million market, and that's just a conservative estimate, and they can do it with retractable roof greenhouses," said Mathers.

She said the gold mine with using retractable roof greenhouses in Ohio tree liner production is that a grower can extend the growing season. Oregon's growing season is 225 days, while Ohio's is only 156 days. "All we are looking to make up is 75 days," said Mathers. "Using retractable roof greenhouses, we can start with growth in March rather than waiting until June. There's the 75 days made up for right there." Mathers said with retractable roof greenhouses, seedlings can be grown into whips under full cover through fall, winter and early spring and, when conditions become more favorable, retract the roofs and/or walls and turn the nursery stock into a commercial production site without ever having to move the trees.

Such convenience, said Mathers, decreases labor and equipment costs. The greenhouses are also affordable to build, costing only $1 a foot for flat-roof houses and $3 foot for peaked-roof houses. "When the average price of a liner is going for $15, it makes economical sense to build a retractable roof greenhouse," said Mathers. "There is a considerable profit to be made here and the thing that many growers don't realize is that it's doable." One argument behind the use of retractable roof greenhouses in Ohio is whether or not they'll stand up to the state's wintry conditions. "Whether the roofs will stand up to snow and ice is something we won't know until we try it. During winter I'd like to think that we'd just retract the roof and let the snow cover the stock, providing insulation during winter - much like you would find in a natural environment," said Mathers.

The researchers are working with red oak, red maple, yellow wood and magnolia seedlings and are hoping to have their first whips by this spring.

The wholesale nursery industry in Ohio is worth about $580 million. The landscape, garden center and nursery sectors combined are worth approximately $2.5 billion annually. Nursery production is estimated to be the fourth largest agricultural industry Ohio, behind corn, soybeans and dairy.

Candace Pollock
Hannah Mathers