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Local Says Rooftop Gardens Preserve Energy and Your Home

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Long used in Europe and Japan, green roof technology is showing up in San Diego. A Kearny-Mesa businessman today unveiled his rooftop garden, which he hopes will have positive effects on the environment. KPBS Radio's Andrea Hsu has more.

Jim Mumford owns the Good Earth Plant Company. It's a nondescript building in an industrial part of town, just across the street from a Pepsi plant. But climb up a metal staircase to the roof, and you find yourself in a different world.

Mumford : Today's the final process in a long road. We're planting today.

Planting a 1,600 square-foot garden, in soil four inches deep.

Mumford : Well I've got prickly pear cactus, I've got a couple Dudleyas, which is a low Succulent, I've got... 

For this green roof, Mumford chose plants native to California -- despite the fact they're harder to grow than others.

Mumford : If I'm going to create an environment, I think an environment that has California natives is better for the birds, the bees and the butterflies.

The cost of it all: $20,000 dollars. Mumford says it's worth it. He believes the garden will extend the roof life two to three times. He says it'll insulate the building, so there will be less noise and lower cooling and heating bills. It won't hold heat the way a standard industrial roof does -- and that means lower air temperatures. Also:

Mumford : This will retain 60 to 80 percent of a rain event. What it doesn't retain filters through the plants and the soil so that the particulate matter gets filtered out -- it also slows it down.

And that translates into less water pollution entering the sewer systems. Still, Mumford says his green roof is somewhat of an experiment. He anticipates he'll kill a few plants here and there -- but hopes it'll pave the way to green roofs across Southern California.

For KPBS, I'm Andrea Hsu.

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