Weather patterns that swing between drought and deluge are becoming more common over much of the U.S. So what’s a home gardener to do? You might think about capturing some of what here in the Pacific Northwest we call “liquid sunshine.” This month we check out one Oregon homeowners’ system that combines practicality with a beautiful low-water landscape.
It all started with too much water. When Debbie Olsen was planning to build her home in the city of Eugene, she discovered that her low-lying property gathered runoff. City code would have required her to pump it uphill to the storm drain. With the help of a savvy landscape designer, she transformed her problem into an asset that benefits her home, the landscape and the greater ecology of the region.
It’s a scheme worthy of Rube Goldberg. Rain hits the home’s steeply pitched metal roof, and then gathers in a flat roof top garden above the front porch. The water slows down as it filters through the plants and is eventually deposited in a handsome 600-gallon concrete cistern, painted in colors to match the house and tucked into the side yard.
In the rainy season, excess water spills from the holding tank into a winding series of bogs, rocky swales and retention ponds, again slowing down as it passes among stones and water-loving rushes. The narrow stream gurgles across the front yard and then arrives on the other side of the garden where a deep rock-filled well allows the rain to slowly seep into the surrounding soil.
In the summer months, the stream goes dry, becoming a well-patterned rocky design element in the front garden. (In spite of its rainy reputation, the Pacific Northwest has a climate considered “modified Mediterranean”—wet winters, drier summers.) The captured cistern water is used to drip-irrigate the roof garden as well the surrounding yard’s xeric plantings. During long dry spells, city water augments the system, timed to enter the tank at off-peak hours when cost is lowest.
If saving rainwater looks good to you, here are some considerations. Green roofs cost more than regular roofing, adding $12 to $30 a square foot. They should be professionally engineered to accommodate the additional weight. Tough low-growing and shallow-rooted plants can be started in your greenhouse using specially designed vegetative roof flats.
The laws concerning rainwater capture vary from state to state. Harvest H20.com is an excellent online resource that will provide you with your state’s requirements. Also, Western Resource Advocates and American Rainwater Catchment Systems Association offer plenty of information to help you succeed.