Thinking like a watershed - a new paradigm in home landscaping

The Merchant of Venice,

The watershed, defined by the perimeter of its highest ridges and the low point towards which its waters flow, can be thought of as a cradle of life which nurtures its member communities through water flow. Described as a basin, the shapes and slopes of its surfaces reflect and absorb sunlight, and as shadows are cast across the land, determine which plant species find favorable growing conditions within it. Some even say the moon, and starlight, also have their influence there.

A back yard or other bit of earth within its boundaries, though small, or identified as "property", can nevertheless make a real contribution to the health and wildlife wealth of the whole, as property value, water conservation, restoration of native-plant communities, and watershed health increase together.

All around the San Francisco Bay, agencies charged with safeguarding the water quality of our streams, wetlands, and bays; and agencies concerned with reducing the flow of "wastestream" headed for landfill, have arrived, with community input, at a vision of watershed health that invites homeowners to think of their properties not just as extensions or adornments of their homes, but as potential jewels in an interconnected web of earth-based living systems.

Look for practical guidance on how to accomplish this through home services, written guidelines, and workshops coming up this spring throughout the Bay Area. One splendid example is Bay-Friendly Landscape Guidelines, fruit of an East Bay community effort sponsored by the Alameda County Waste Management Authority, available at www.stopwaste.org or by calling (510) 614-1699. This user-friendly guide, featuring photographs and quotes from people who work in landscaping, offers succinct how-to help in adapting or creating a home landscape in line with watershed goals. (ACMA markets the manual to landscape professionals, but it is, in fact, one of the best available guides for Bay Area homeowners, as well.)

The guide is organized around seven critical factors, which taken together create life-giving webs of soil, plant life, and water flow; conserve air and water quality; and prevent pollution. My abbreviated version of this list follows:

landscape locally - understand the climate; patterns of sun, shade, and wind; soil composition; and topography of your place;
landscape for less to the landfill - by grasscycling, producing mulch and compost at home;
nurture the soil - protect it from compaction, defend against erosion, amend it;
conserve water - create soils that resist summer dryness with compost and mulch, grow California natives or Mediterraneans, minimize the lawn;
conserve energy - plant trees to moderate building temperature, shade paved areas to reduce the heat-island effect, specify local products and suppliers;
protect water and air quality - use Integrated Pest Management, eliminate high-input decorative lawns, keep soil covered;
create wildlife habitat - choose California natives first, conserve or restore natural areas and wildlife corridors.

Although all seven factors are important and contribute to the whole, in this article, we explore two: nurturing the soil and conserving water, which taken together form the very foundation of your garden.

What does "nurturing the soil" mean? In most cases, it means aerating, through forking or digging, and amending, by incorporating good quality compost. Although the prospect of the work might seem daunting to a non-gardener, once planting areas are aerated and amended, it's done forever - as long as one top-dresses with a humus-laden compost, once or twice a year. In this way, garden soil comes to act and feel like the spongy base of the forest floor.

The January issue of Bay Nature magazine features an information-packed feature on soils, to help homeowners understand what's going on underground in their own back yards. It makes unmistakable the relationship among soils, water quality and water conservation:

"Soil is also inseparably linked to water supply and water quality. The amount of water in our aquifers, rivers and lakes depends partly on the health of the soil. A topsoil that has good structure [from aerating and amending] and is covered by vegetation [through planting in layers] will absorb almost all the water that falls upon it. Once [water is] absorbed, the entire soil body acts like a sponge, at first holding large volumes of water, then slowly releasing it to aquifers and surface water bodies. The living soil also cleanses the water passing through it, filtering out particulate matter and absorbing [and decomposing] pollutants." [Words in italics are my additions.]

In a cultivated garden, a plant placed in such a spongy bed will reward you by thriving immediately, and will grow well throughout its life, as long as the soil sponge stays sufficiently damp. California natives, once established in an uncultivated summer-dry garden, need almost no water. (See Plants and Landscapes for a Summer Dry Climate, available from the East Bay Municipal Utility District, for an extensive listing and gorgeous photographs of plants that do well in our dry California summers.) These two poles can define the end points of a continuum between wet and dry ground in a home landscape.

These days, many homeowners, especially those with property bordering on wild areas, utilize this continuum to create hydrozones, so that those plants requiring the most water and/or cultivation are closest to the house - welcoming flower borders, fruits, and kitchen gardens - and those California natives which thrive with no summer water, furthest away. This is one more way to make sure no drop of water gets wasted, as plants with similar needs are grouped together in the planting design. (For photographs of this kind of landscaping in an oak woodland, see Bay Nature's Gardening for Wildlife Supplement, available from its editorial offices at (510) 528-8550.)

To get a start on conserving water, call your water district. Invite one of its reps out to help troubleshoot your irrigation system for leaks. Or sign up for one of its soil-water monitoring programs to provide yourself with climate-sensitive irrigation run times specific to your locale.

According to agencies that track summer water use, too much water is wasted by setting digital controls at the beginning of the season, letting the system run on, and never adjusting the controls, even when soil and weather conditions change. In my neighborhood, on a summer walk, it is usual to see eight irrigation systems overwatering lawns within two blocks.

To experience the delight to the senses, and the intimacy of a real connection to your bit of land, feel how the water flows through it by becoming the water-bearer yourself. Consider working with the simpler watering tools of an earlier time. Hand-held water wands, combined with a set of fan or overhead sprinklers, may be able to deliver water more effectively, for less cost in time and energy, and less maintenance hassle, than your digitally controlled irrigation system, as its plastic parts become brittle, clogged, or inoperative very quickly. If your cultivated summer-garden beds need consistent water for vegetables or other annuals, the simple tools may do a better job of "wetting the sponge" than either microsprays or drip emitters, by applying a flow of water with a gentleness that prevents compaction and matches the soil's ability to absorb it. The observant eye can easily learn to tell when the soil has reached a saturation point.

Guided by your hand and eye, these watering tools can further apply a flow that reaches the whole planting area, much as rainfall does, allowing plants the natural ebbs and flows of spreading that we so admire in a natural setting. Once you understand your soil's capacities, you have the option of setting timers on these sprinklers if you wish.

For a completely summer-dry landscape of native plants, on the edge of a property adjoining the wild, or around a cabin in an uncultivated oak woodland, the most elegant, labor-saving watering scheme I've seen is a ½" plastic pipe with drip holes laid under a mulched planting area. Once every two weeks the gardener arrives with a hose, connects the drip line to the faucet, and lets it run for half an hour. In an uncultivated landscape this is sufficient to help new plantings of natives get established and stay green throughout the summer. By becoming this careful, observant, and appropriate with our watering strategies, we find we no longer need the amount of summer irrigation water we thought necessary.

Finally, notice the plant communities native to the watershed around you.

Do you see remaining stands of coast live oak, a stand of redwoods in a canyon, a hillside covered with coastal scrub? Many of the most handsome, smaller native trees and shrubs are both evergreen and highly garden-adaptable, capable of providing you, once established, with the cooling refreshment of summertime green with no summer water. Lovely flowers and edible berries for both people and wildlife increase the gift.

According to Alex Forman of the Board of Directors of the Marin Municipal Water District, about 40% of our summer water use goes to irrigating gardens. Nurture the soil, and get agency help conserving water. Make use of the many programs and services espousing the new landscaping paradigm in your area. Borrow from native-plant communities, and your landscape will thrive on little water while you save time, water, and dollars on your water bill.

With a little collective muscle, according to Alex, MMWD consumers could achieve at least a 25% reduction of the total, for a savings of 350 million gallons of water, or 1,075 acre feet in one growing season, with corresponding savings in other counties around the Bay! Let's go for it.

Coming events this spring

Bay-Friendly Gardening. Series of eight workshops starts Sat., March 19, in both Oakland and Livermore, plus a garden tour Sun., May 15. For more information, or to register, go to www.BayFriendly.org

To volunteer to help with the garden tour, contact Jeanne Nader by or (510) 614-1699.

Garden Design for Color and Climate - and Leaving the Chemicals Behind, Sat., March 5. Design your home garden with assistance from professional designers. Work with nature, bring California native and Mediterranean plants into your garden, learn the significance of plant color and shape. Subsidized by the Marin County Stormwater Pollution Prevention Program (MCSTOPPP). At College of Marin, with designers Terumi Leinow and myself, Katharine Cook; and Martha Berthelsen, a naturalist and instructor in Bay-friendly gardening. $25, (415) 485-9368. Class is full; waiting list only.

Bringing Back the Natives Garden Tour, Sun., May 5, 10 am to 5 pm, free to the first 50 people who register. Pre-registration required. Contact:

Tour features a variety of landscape gardens, featuring water conservation, use of native plants, and wildlife-habitat restoration.

H₂O How To, Sat., April 23, 10 am to 3 pm, Exhibition Hall of Marin Center. Free event offers displays of California native and Mediterranean plants by local nurseries, irrigation-system advice and "fix-it" booth, educational booths, and talks designed to help Marin homeowners learn how to conserve water while creating beautiful gardens at home. Sponsored by Marin Municipal Water District.

Gardening with Birds and Butterflies, April 30, 9 am to 1 pm, College of Marin. Sponsored by MCSTOPPP. Create a beautiful healthy garden using fewer pesticides. Learn how to attract beneficial insects; create habitat for birds and butterflies. Includes extensive resource binder, colorful insect I.D. guide, and your own worm-composting bin. (415) 457-8811, ext. 7751 or www.MarinCommunityEd.org

Katharine Cook is a landscape designer who brings California natives, Mediterraneans, and plant communities from other parts of the world into a variety of classic design settings. She received training in biodynamic horticulture at Green Gulch Farm, where she lived for 20 years, and is a founder of that garden. She can be reached at (415) 457-6368 or by