Rain, rain, rain! Rain causes erosion, which can be a problem for gardens, especially those on a steep slope. Planting native perennial grasses with their deep fibrous roots will help hold the soil. (Don’t plant pampas grass, it’s an invasive non-native.) Mulch can be important, too. It will spread the water more evenly over the soil and prevent ruts from developing.
Water from downspouts should be directed away from the house, but allowed to percolate back into the soil. Many homeowners are using pervious concrete, pictured, for driveways and parking areas. This material has high porosity. Pervious (or permeable) concrete consists of cement, coarse aggregate and water with little to no fine material. It reduces runoff and allows groundwater recharge.
The United States Environmental Protection Agency says use of pervious concrete is an important management practice for reducing stormwater runoff.
— Katie Martin, UC Marin Master Gardener