Q&A: Expert answers to landscape design questions
By Margie Grace
Q: How do you practice water-efficient design?
A: Always start with the soil: healthy soils, healthy water infiltration, air circulation, nutrient flow. Add microbes, organic material, and minerals as needed for the plants you intend to grow. If you’re watering plants that are never going to be healthy, you’re wasting water.
Collect rainwater on site and use it for landscaping — from simple swales/grading to sophisticated collection, storage and distribution systems.
Match your plantings to the environment you’re in:
In Southern California, that means using plants that are adapted to seasonal winter rain and extended periods of drought — natives and other drought-tolerant species.
In Portland, that means using plants that are adapted to year-round rainfall.
Mulch to conserve water, regulate soil temperature and prevent weeds (weeds suck up water intended for landscape plants). Plant for 100 percent ground coverage at maturity (roots stay shaded by plant’s own foliage, reducing soil temp and water demand).
Use fewer plants — areas mulched with wood chips, gravel, pebbles, stone and boulders don’t require irrigation.
Water features
Recirculate the water in your water element.
Do whatever you can to reduce evaporation (for example, cover the water reservoir/pond, minimize surface area of open water, fewer waterfalls/splashing) and water loss (water splashing outside of or leaking from the water element).
Do anything you can to reduce evapotranpiration. For example, if there is a lot of wind, shelter plants with a windbreak or pick plants that are tough/sclerotic.
Irrigation system
Irrigate in a way that encourages deep rooting (deep, infrequent watering vs. shallow, frequent watering). Deeply rooted plants pull water from deeper, typically moister, soil layers.
Use drip where possible. Use efficient heads where sprinklers are needed.
Design so that water lands where it’s wanted, not on sidewalks or hardscape.
Application rate: never allow runoff of irrigation water. On a hill, this means drip application or multiple short watering cycles to allow for percolation.
Use “Smart” irrigation timers (tied to real-time weather data by satellite).
Irrigate when evaporation rates are low (early mornings are best in warm climates).
Being water wise reduces water use, water bills, maintenance, and the environmental footprint; and it is simpatico with natural surroundings.
Margie Grace, founder and one of the principals of the award-winning Santa Barbara-based firm Grace Design Associates, Inc., Santa Barbara, Calif., is a landscape designer and a licensed landscape contractor. She holds a Bachelor of Arts degree in biology with a minor in geology, awarded in 1981 from the University of California at Santa Cruz. She has also studied landscape design and illustration extensively at the University of California at Los Angeles.
