In Santa Monica,California water is a scarce resource,as it is in many parts of the world, and more and more water is a major issue also for gardening. Most traditional suburbs have gardens with non-native plants that are not accustomed to the hot and dry climate and require constant watering and maintenance. Large expanses of lawn require frequent mowing. The average lawn-mower uses 11 times the air-pollution of a new car for each time mowing.
In order to raise awareness of the limited water supply and showcase the advantages of native landscapes, the city of Santa Monica created a demonstration project that compared two adjacent front yards: a native garden (left) and a traditional garden (right). The project allows visitors to directly compare the visual appearance and maintenance statistics of the two sites.
The traditional garden represents the typical landscape in suburban Southern California. Grasses, shrubs, and flowers are exotic species that originated in other parts of the world. Designers installed a standard, user-controlled sprinkler irrigation system, which distributes water to all plants, regardless of need. Sprinkler water often evaporates before ever hitting the ground
In the sustainable alternative, the designer installed only plants native to southern California. A water-efficient drip irrigation system was installed and adjusted for each individual plant. A weather-sensitive irrigation controller automatically adjusts water output based on daily precipitation, enhancing efficiency.
To keep the traditional garden green and flowering, frequent applications of fertilizer and pesticide are required. The average home gardener uses 10 times more toxic chemicals than a farmer. During rain events, these chemicals are washed away by stormwater into the city’s water supply, increasing water pollution and disrupting aquatic habitats.
In the native landscape, designers replaced the concrete on the handicap ramp with a porous material made from decomposed granite. The new surface allows rainwater to seep into the earth rather than running off the property, into the street and the Santa Monica Bay.
The city of Santa Monica tracked the water usage, yard waste and maintenance hours of both gardens over a four year period. The native garden used 77 percent less water, produced 66 percent less yard waste, and required 68 percent fewer maintenance hours than the traditional garden.
The native garden cost $16,700 to install compared $12,400 for the traditional garden. Despite its higher initial cost, the native garden’s lower maintenance requirements translate into $2,200 per year in cost savings.
Source ; American Society of Landscape Architects.