In the Garden: Xerophytic landscaping, reducing water use

Dana Kelley Bressette

In the Garden

Ever wonder why we have predominantly evergreen forests in the Pacific Northwest? Whereas, at our same latitude in the east, New Brunswick, Canada, has mostly deciduous trees that exhibit brilliant colors in autumn.

Most of the world thinks it rains all the time in our region, but one of our secrets is our dry summers. In regions with summer rains, trees that lose their leaves in the winter have all summer to photosynthetically replenish their energy. Evergreens, however, are adapted to be able to photosynthesize whenever conditions are favorable.

Therefore, in the Pacific Northwest, evergreens that have limited moisture in the summer can grow at other times of the year.

We call our mild, maritime climate with relatively warm, wet winters and cool, dry summers, a winter rain or cool Mediterranean climate. Most other winter-rain climates are warmer, as found in parts of Chile, South Africa and Australia. For plants that may be better adapted to drier Northwest gardens, horticulturists look for plants from those regions.

Although native plants are obviously the best adapted, plants from other winter-rain regions also do well in our drier landscapes.

From Chile: Escallonias have glossy evergreen leaves and small pink flowers; Pernettyas, (Gaultheria mucronata) come in different varieties with shiny berries that range from white, pink, red and purple to nearly black — all with a metallic sheen; Darwin Barberry (Berberis darwinii) has fountain-like growth with showy yellow flowers and blue berries favored by birds. Its spiny stems make it and excellent barrier shrub.

From South Africa, Cape Fuchsia (Phygelius capensis) has loose clusters of red-orange flowers.

From Australia, some of the hardier Eucalyptus trees, such as the Cider Gum (E. gunnii), may be successful in certain micro-climates.

Several familiar landscape plants come from the Mediterranean, including true Cedars (Cedrus sp.), Mediterranean Heaths (Erica x darleyensis hybrids), Strawberry Tree (Arbutus unedo) and the ever-popular Lavender (Lavendula sp.).

Plants adapted to withstand dry periods usually have thick, waxy leaves. Hairy leaves provide protection against drying winds. Gray or silvery foliage reflect some of the sun’s rays. Look for those characteristics when you choose “drought-tolerant” plants.

Many regions, such as the southwestern United States, are facing severe water shortages. Some conscientious, environmentally responsible citizens who are eliminating water-guzzling lawns and replanting with natives have had to battle homeowners’ associations because the new look of their landscape didn’t fit the accepted standard!

Currently, in the Northwest, we rarely have water restrictions — but we may find them occurring more frequently in the future.

Add compost to soil to increase water-holding capacity. Mulch to keep the soil cooler and moist longer. Reduce turf areas by planting native groundcovers, or try an “eco-lawn” that requires less irrigation.

In order to irrigate efficiently, group all water-loving plants. Create focal points by planting colorful annuals in small areas or in containers. To determine how long to irrigate, measure how long it takes to fill a tuna can 1 inch deep, take an average of several places closer and farther from the sprinkler head (different soil types may require more or less).

It’s better to irrigate deeply and less frequently to encourage plants to grow deep roots. Watering during the cooler, early morning hours prevents loss due to evaporation. Soaker hoses or drip irrigation systems deliver water just where it’s needed.

Some of the newest, more sophisticated irrigation systems have moisture sensors; some can even tie into the Internet and make adjustments using information from local weather reports.

Remember that any new landscape will have to be irrigated for the first one to three seasons in order to establish good root systems.

In the Garden columnist Dana Kelley Bressette can be reached by e-mail at skyenergy@centurytel.net.