Designing Landscaping In The Pacific Northwest

Learn to design a landscape on the Pacific coast, in the Cascade Mountains, or on the shrub-steppe of Oregon and Washington.

There's a good reason Seattle is called The Emerald City. The mild, rainy weather along the coast and in the mountains of the Pacific Northwest creates the perfect conditions for a flourishing, green landscape. East of the Cascade Mountains, in the rain shadow of the peaks, lies the semi-arid shrub-steppe with its sage brush and desert wildflowers. With the right plan and a little know-how, a thriving garden can be created in any of these climates.

Coastal

Winds, salty sea spray, and sandy soil make landscaping on the Pacific Northwest coast a challenge. Before anything is planted, the nutrient-poor soil should be enriched with a minimum of a 3 inches of organic material such as compost or manure. Another important step to take is that of creating a line of defense from harsh maritime conditions. This type of barrier around the landscape can be created by planting a row of tough shrubs like bayberry (Myrica pensylvanica), rugosa rose (Rosa rugosa), or beach pea (Lathryrus japonicus) then, closer to the house, a line of evergreens, such as red cedar (Thuja Plicata) or Sitka spruce (Picea sitchensis). Once this border of vegetation is established, more sensitive plants can be grown behind it. Starting a lawn by the coast can also be difficult, but it can be done by first mixing at least 6 inches of organic material into the soil then planting hardy grasses like chewing fescue or hard fescue. Erosion-prone sand dunes, a common seaside landscaping problem, can be stabilized with natives like dunegrass (Elymus mollis), beach pea, or beach morning glory (Convolvus soldanella), rather than the non-native American or European beach grass. In addition, shrubbery can also reduce erosion by limiting the rainfall that reaches the ground.

Mountain

With its short growing season, rocky soil, and the shade cast by fir forests, the Cascades would seem a difficult place to garden. Fortunately, the fairy tale alpine meadows and the rich diversity of plant life in the forests show how much this climate has to offer. Three types of gardens do well here. Shade gardens work well in landscapes surrounded by fir forests, wildflower meadows are perfect for open spaces, and rock gardens are appropriate for sunny, hillside locations.



In a shade garden, native plants like salal (Gaultheria shallon), Trillium parviflorum, and maidenhair fern (Adiantum pedatum) will flourish. Somewhat sunnier locations are natural for wildflower meadows. Because of the frequent rain, traditional lawns will be plagued with moss and ferns. By using an open space to cultivate native wildflowers instead, you'll reduce maintenance time and attract butterflies and hummingbirds, as well. Try yarrow (Achillea millefolium), twinflower (Linnaea borealis), and tiger lilies (Lilium pardalinum) here.

As frequent as rainfall is in spring and autumn, summers can be surprisingly dry and hot. If you're landscaping on a rocky hillside, choose heat-tolerant plants like saxifrage (Saxifraga tolmiei), scarlet paintbrush (Castilleja miniata), or even the non-native hens and chicks (Sempervivum arachnoideum).

Landscaping trees that thrive in the Pacific Northwest include vine maple (Acer circinatum), Pacific dogwood (Cornus nuttallii), Sitka mountain ash (Sorbus sitchensis), and Pacific ninebark (Physocarpus capitatus). The native shrubbery such as serviceberry (Amelanchier arborea), huckleberry (Vaccinium ovatum), and salmonberry (Rubus spectabilis) can be used to create borders and provide edible berries. If you're wildcrafting, though, keep in mind that a number of native plants, such as bear grass (Xerophyllum tenax) and Trillium parviflorum, are protected as endangered species.

High desert

As if the coastal and mountain ecosystems of the Pacific Northwest weren't unique enough, east of the Cascades lies a desert-like steppe. In this area, lack of water, cold nights, and high winds all challenge home landscapers. To make full use of the rainfall, before you plant, consider shaping the land around your home to create gentle slopes that direct water into the garden. Also remember to group plants with similar water requirements together.

Xeriscaping, landscaping with drought-tolerant plants, is the technique to use in this climate. Paintbrush flowers (Castilleja ssp.), larkspur (Delphinium ssp.), and evening primrose (oenothera ssp.) add color, while ornamental grasses such as yellow pampas grass (Cortaderia selloana), blue oat grass (Helictotrichon sempervirens), and blue-bunch wheatgrass (Agropyron spicatum) provide water-saving alternatives to large lawns. Trees that do well on the shrub-steppe include dwarf conifers like pine, spruce, and juniper. For border shrubs, try sage brush (Artemisia ssp.) or crape myrtle (Lagerstroemia indica).

In this arid environment, efficient irrigation is vital. Drip irrigation systems will work best for small plants and vegetables, while bubblers can be used to deliver the extra water required by trees and large shrubs. Contrary to popular belief, water features like ponds and fountains are perfectly suitable for dry-climate gardens. Because these features re-circulate their water and evaporation can be reduced by proper shading, these water features actually use far less water than a lawn would.

With three distinct ecosystems and additional microclimates within these, the Pacific Northwest offers something for every gardener. Whether you're planning a coastal landscape, an alpine meadow, or a xeriscape garden on the steppe, learn to work with the environment and use native plants and you'll be able to create one of the lush gardens the Pacific Northwest is famous for.

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