Some gardeners work to change conditions in their yard to create havens of greenery and blooms with plants that wouldn’t grow there otherwise. They amend the soil to suit plants’ needs, they water a lot during the summer, and they give added protection to non-hardy plants.
More and more gardeners today are saying “No!” to extra tasks, choosing to work with nature instead of against it. They are using nature as a model in creating yards and gardens that reflect the natural beauty of the place where they live. They’re determining the aspects their yards share with surrounding natural areas-sun, shade, rocks, slopes-and they’re choosing plant communities (groupings) that exist in similar natural settings. Perhaps without knowing it, these gardeners are reclaiming their sense of place.
Here in Washington State, gardeners talk about the “wet side” and “dry side” when referring to the two sides of the Cascade Mountains, but our landscape is much more varied than that. Anyone traveling across the state can start at the ocean shoreline and ride through lowland forests, mountain forests, grasslands, and desert all in a matter of hours. As the scenery changes, the traveler is actually passing through different ecosystems. Ecosystems are areas with communities of plants and animals closely related to their physical surroundings.
Washington State is home to nine different ecosystems, all of which can be seen traveling east to west on Highway 20, and all but one can be viewed from I-90.
My Spokane yard is in what’s called the Ponderosa Pine ecosystem. This ecosystem extends through much of eastern Washington in areas between 2,000 and 3,000 feet in elevation. It blends at its upper edges with the Mountain Forest system (3,000-5,000 ft.) and at its lower reaches with grassland and sagebrush systems. Winters in the Ponderosa Pine system are cold with sub-freezing temperatures; summers are hot and dry. Only 10 to 20 inches of precipitation fall yearly here, classifying it as “high desert” in some guide books.
When we bought our house in 1996, the backyard was a large rectangle of lawn grass with a single line of shrubs around the fence. Several towering pine trees stood scattered throughout the lawn. Aspects this yard shared with nearby natural areas: pine trees. No understory shrubs and plants, no soft layers of accumulated pine needles, no chattering birds or chipmunks, no seasonal interest. Our yard simply had turfgrass struggling to survive in the shade of pines. It had most likely been mowed, fertilized, and watered on a regular basis since its planting sometime in the 1950s.
Our goals in naturalizing the backyard were to do less watering, mowing, and raking of pine needles and to attract more wildlife. We kept enough of the lawn to suit us, but over half of our yard is now like a sanctuary with all the sights, sounds, smells, and feel of a Ponderosa Pine forest.
How to naturalize around existing trees: Stretch a rope or garden hose along the ground to mark the area under trees to be naturalized. It is not necessary to remove the turf if it is killed first and covered with a layer of top soil/compost mixture. There is a quick way to kill turf using an herbicide and a slower, non-chemical way:
Quick method: Use Round-up herbicide according to label directions. When turf is completely dead-after about two weeks-cover it with a three- to four-inch layer of compost/top soil mixture. Add new plants by planting right through the topsoil and dead turf.
Slow method: Spread at least a quarter-inch layer of newspapers over the area of turf to be eliminated. Wet the papers to keep them in place, and cover with a three-inch layer of topsoil/compost mixture. Leave in place for at least three months. The newspaper layer prevents grass from growing through the topsoil. Add new plants by planting right through the topsoil and dead turf.
Choose plant communities known to be associated with Ponderosa pines by observing them in nature or referring to native plant guides and nursery catalogs. (See sidebar.) Non-native plants can also be used as long as they are shade- and drought-tolerant and hardy. Place plants where they can grow to their mature size without pruning or transplanting later on. Layering vegetation under the pines with large shrubs, small shrubs, and groundcover plants will attract and support a variety of birds and beneficial insects.
While new plantings are getting established, water regularly the first summer season or two and maintain a layer of fine bark mulch to keep weeds out and conserve soil moisture. After the second summer, watering once a month may be adequate, and the fallen pine needles will take over as natural mulch. As the plants increase in size, watering and weeding tasks are greatly diminished or eliminated.
Tonie Fitzgerald is a WSU/Spokane County extension agent in horticulture and author of Gardening in the Inland Northwest (Washington State University 2001).