by David Goldstein, VCPWA, IWMD
The ongoing drought and other recent events have stressed local landscapes, and recent warm and dry weather may make rains seem distant, but as House Stark says in Game of Thrones, “Winter is coming.”
When rains hit weakened landscapes, the result is often erosion. If topsoil washes off your property and into storm drains, not only do you lose nutrients needed for gardening, but you also risk polluting natural habitat. Sediment-laden water flowing from storm drains into waterways can bind to fish gills, impairing fish’s ability to breathe. Murky water also blocks sunlight and inhibits the growth of plants necessary to sustain natural habitat. Runoff can also carry harmful metals, pesticides and fertilizers.
If you have recently lost established plants holding the soil of your landscape, or if you have only weakened or damaged plants, you may consider several options to prevent your topsoil from washing down storm drains and polluting waterways.
Straw wattles are one of the simplest and least expensive immediate measures to prevent erosion. Wattles are long tubes full of straw, mulch chips or coir, which is coconut mixed with straw. Wattles are placed across a slope, so they slow runoff, allowing water to flow through while holding back sediment.
Jason Stetler, a landscape architect with Scarlett’s Landscape, recommends aligning wattles at 15 foot intervals, like contour lines, depending on the angle and distance of a slope. Between rows, he often adds plants suitable for a Mediterranean climate.
Secure wattles into trenches a few inches deep, and use stakes on both sides to prevent them from washing away and clogging nearby storm drains. Jute and fiber blankets can provide similar protection on flatter areas, and sandbags can direct water away from erosion prone areas.
For longer term plans, consider native vegetation such as woody shrubs and natural grasses to stabilize soil and filter pollutants. Permeable hardscape is also useful to slow, spread, and sink water, rather than channeling rain into soil robbing torrents.
If you are considering working with a professional landscape company to plan or plant your garden, the sooner you start, the more likely you are to be prepared for the first major rain of the season. Lupe Pardue , Operations Manager of Halter Encinas Enterprises, reports she has received calls from 50 of the company’s 250 regular residential garden maintenance customers in the past two weeks, and these customers, as well as others, are eager to plan new landscapes.