Why plant a rain garden? You might assume that something with the words rain and garden next to each other does not immediately sound feasible for drought-stricken Southern California. But rain gardens are a form of water harvesting — a way to capture and filter water that would otherwise flow into storm drains and eventually, the ocean. They typically include native perennials, shrubs and small trees planted in a small depression designed to temporarily hold and soak in rainwater runoff that flows from impervious surfaces such as roofs, driveways, walkways and compacted lawn areas. Compared to conventional lawns, rain gardens allow for 30% more water to soak into the ground.
Pictured below is a residential rain garden I visited as part of the Mar Vista garden tour a few weeks ago. The garden was installed in 2012 and is watered by hand every 2-3 weeks during the dry season. The Surfider Foundation has some very useful resources for removing your lawn and creating ocean-friendly rain gardens.