Wet winter and dry summer gardening methods

Here in the Pacific Northwest, where climate change is already making subtle shifts within the region’s modified Mediterranean environment, it’s time to consider a future where all landscapes are virtually irrigation independent.

Over the past six years, mercurial winter weather patterns have left us with annual snow amounts that are either nonexistent or barely sufficient. Without these frozen reserves, water demands during the summer months can outstrip the supply.

When arid summers are combined with future winters that are likely to be both dryer and warmer, it makes sense to create waterwise gardens that strike some sort of balance on Mother Nature’s scale.

The concept of so-called “dry gardening” uses plants that thrive without much fertilizer, insect/disease control or water.

When managed in conjunction with soil building, irrigation and excellent drainage, the end result is a lush, dramatic plant environment that, when mature, may only need irrigation once a month - even during the hottest season of the year.

Author Ann Lovejoy, who gardens on Bainbridge Island outside Seattle, Wa., has long been a proponent of dry gardening. Her gardens are beautiful — full and diverse, with french drains disguised as gravel pathways and mounded beds bursting with fragrant herbs, perennials, shrubs, trees and vegetables.

Lovejoy waters her main garden about once a month in high summer and little or not at all the rest of the year. Exceptions are made for young and new plants (they’re watered as needed), veggies and also for containers (they’re watered weekly or biweekly).

The key to her success? Soil and bed preparation. Lovejoy believes that creating mounded, naturally-shaped beds atop the native heavy clay soil is the secret. Water then drains into the gravel pathways, which means that her plants never get wet feet.

Our summers here in Western Oregon are definitely warmer than a typical Puget Sound summer. But Lovejoy’s basic tenants of dry garden construction stand up regardless of the location:

n Build mounded beds for good drainage: This is not the same thing as a raised-bed with wooded or plastic sides. Instead, it’s a bed that can be as low as 18 inches or up to 3 feet tall in areas where added height contributes both form and function.

n Make the beds big enough to function efficiently: The idea, according to Lovejoy, is to create beds that are in scale with both the house and surrounding landscape. They should have strong shapes and clean lines, with a width that can vary anywhere from 4 feet to 40 feet.

Such beds require a lot of soil. Large quantities can be delivered straight to your site, or you can haul it yourself (the main reason I’ll never let my husband sell our aging but still functional truck!).

n Mulch generously with compost and/or gravel: Mulching with a 2- to 4-inch blanket of organic material is an excellent way to counter fluctuations of temperature and drought. It keeps most weeds down, locks moisture in, feeds the soil and looks terrific. Crushed gravel (never pea gravel or river gravel — it doesn’t filter water correctly) can be used to top-mulch over compost for drought-loving Mediterranean plants that need extra heat or drainage.

n Pick the right plants for your site: It’s important to understand just how much sun your garden receives. Most dry-garden models are for sun-loving species, says Lovejoy, but it is possible to create a dry shade garden,

We’ll be getting into plant specifics in next week’s column, but remember that even drought-tolerant plants need regular watering until they’re established.

n Adjust your irrigation habits: Overwatered plants have shallow root systems which make them susceptible to many different ailments. Healthy roots grow deep and strong, which encourages species longevity. To ensure this trend, Lovejoy recommends slowly changing your watering habits. No landscape, for example, needs to be watered every day.

Instead, pay closer attention to weather patterns this coming season and make some adjustments. Spread a fresh layer of mulch on beds after they’ve been tidied and are still moist from a recent rainfall; try irrigating your borders just twice a week after warm weather arrives; mulch lawns now with a half-inch of compost and water your grass, deeply, just once a week.

For more information, check out the “Saving Water Partnership” (www.savingwater.org). This group of 18 Seattle-area utilities got together about seven years ago to fund water conservation programs within the city and the surrounding King County area.

Their unique community partnership has resulted in a wealth of free information (garden guides, brochures, flyers, e-mail newsletters, a natural lawn and garden hotline, links to tools, products and professional services), all available through their informative website.

Don’t forget —- next week we’ll be focusing on plant species that thrive in our wet winter/dry summer climate.



<i>Sarah Robertson is a Eugene-area writer</i>