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The greenhouse effect

The greenhouse effect

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    With a total growing area of more than 54,000 square feet, Denver's greenhouses produce most of the annuals that grace one of the nation's largest municipal park systems. Photo: Stan Obert, Denver Metro Convention and Visitors Bureau

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    Starting from cuttings or seed, staff at Mobile, Ala.'s greenhouses and nurseries grow a variety of trees, shrubs, and plants. Photo: Dan Otto

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    Although Wichita, Kan.'s greenhouse stopped propagating plants in the early 1990s, it's still used to house greenery before planting time. Photo: Thane Rogers

The oldest resident of Mobile, Ala., is Duffee Oak—tall, strong, and silent, and looking pretty good for a 300-year-old. The majestic tree is just one of the city's 3000 oaks that have passed the one-century mark.

From the impressive Duffee Oak to the kaleidoscope of flowers adorning city streets, plant life is important to the 200,000 people who call Mobile home. Most of this fabulous flora has its roots in the city-run greenhouse. While many greenery-minded municipalities buy their bedding plants, shrubs, and other vegetation from private nurseries, some parks departments have found that maintaining a city greenhouse saves money, provides flexibility, and improves constituent relations.

Mobile's greenhouse has doubled its capacity over the past decade to keep up with growing (no pun intended) demand for foliage around town. The facility generates nearly all of the annual plants used in the city's flower beds, starting most from seed. Ground cover, woody ornamentals, and trees are cultivated for parks and rights of way. The greenhouse staff grows the contents of the 150 hanging baskets that line the downtown streets, and they sometimes help with the beautification of neighborhood entrances by supplying flowers and other landscaping plants.

Greenhouse crews put forth a great deal of effort toiling in the soil, but the amount of green they raise can lower a city's landscaping expenses.

“The greatest benefit in growing our own plants is the operating supply budget,” says Dan Otto, Mobile's parks superintendent. “We couldn't afford to buy the number of plants we produce.”

Flexibility is another reason cities grow their own greenery.

Denver runs one of the country's oldest greenhouse operations (started in 1890), and grows a stunning array of roses, shrubs, annuals, and perennials—more than 300,000 plants each year.

“We get much better diversity than we would if we didn't grow our own stuff,” says greenhouse superintendent Gary Douglas. “We can grow unusual things, any quantity we want—there's no limit to what we can do.”

However, as Wichita, Kan., landscape supervisor Thane Rogers points out, city-run greenhouses can save money, but they don't run themselves. Inadequate funding and staffing can make it impossible to keep up with community growth.

“As budget and staffing are reduced—or at least not increased—and responsibilities increase due to more city development and annexation, quality production suffers,” says Rogers. “You reach a point where quality standards are better met by private sources.”