Water – A Precious Resource in the Garden
By Paula Rodriguez de la Vega
One of the wonderful things about the Okanagan is that it is one of the driest and hottest areas in Canada. This means we have a unique natural landscape with plants that have adapted to the arid conditions.
Ecologists call these landscapes the South Okanagan grasslands. They are divided into two broad ecosystems: bunchgrass and shrub-steppe. The shrub-steppe grasslands occur in the hottest and driest environments of the valley bottoms, and are further divided into sagebrush steppe and antelope-brush steppe. All of these different habitats have their own plants and animals adapted to live there.
Water is the limiting factor. Each plant and animal species living here has adapted to the little water available. On average, the south Okanagan only gets about 8-10 inches of rainfall a year.
Many of the plants go dormant not only in winter, but also during the stifling dry summer. It’s quite amazing really. Take grasses for instance, many of them grow, bloom, and go to seed in a short period of time in spring, when it rains the most. Some drought-tolerant plants will hold off blooming until late summer or fall, when it’s cooler and the next period of moisture arrives. Some plants have small, waxy, or hairy leaves to prevent water loss through evaporation.
So what does this have to do with gardening? Xeriscaping is a landscape that uses plants that have low water requirements, making them able to withstand extended periods of drought. Xeric landscapes are a conscious attempt to develop gardens which are compatible with this beautiful, dry environment.
Shrubs like Saskatoons and Mock-Orange have bright white flowers in spring. Add a splash of silvery foliage with a Big Basin Sage or a Rabbit brush. And some colour with Brown-eyed Susans and White Tufted Prairie Asters. After about a year or two of being established, all these thrive with little to no water in summer.
Water being the limiting factor needs to be used sparingly. Irrigation needs to be planned carefully.
Here are some basic Water-Wise Tips:
Water deeply, thoroughly, and less often. This will encourage plant roots to grow deeper to search for water, allowing them to survive periods of drought better.
Water your plants as close to their roots as possible to ensure the least amount of water evaporates before your plants can absorb the water. Drip irrigation is a great way to do this. It offers increased watering efficiency and plant performance when compared to sprinkler irrigation.
If you have sprinkler irrigation: The permanent underground sprinkler system can be more water efficient than a hose-end sprinkler if it is adjusted and timed correctly. Make sure the sprinkler heads are adjusted to avoid watering sidewalks and driveways. They won’t grow! Also, a properly adjusted sprinkler head sprays large droplets of water instead of a fog or mist which is more susceptible to evaporation and wind drift. Make sure the soil can absorb the amount of water you are applying without creating runoff.
To test how many inches of water are being applied, set out several empty tin cans (e.g. tuna or cat food) within the sprinkler reach. One inch a week should be more than enough for regular lawns. Depending on what kind of grass you have, letting them go brown in summer as they do in nature, will not harm them. Drought-tolerant plants are fine with about ½ and inch every two weeks or so, if that.
Watering should be done when the weather is cool and calm. Early morning is best, then evenings.
Mulching also conserves water by reducing evaporation from the soil. It also reduces weed populations, prevents soil compaction and keeps soil temperatures moderate. For shrubs and trees, you can use organic mulches like bark, compost, woodchips; or inorganic materials like gravels or limestone. Leave grass clippings on the lawn. They contain moisture and nitrogen your lawn can use. Aerate and mulch or top dress your lawn with organic materials. Aeration helps water and nutrients penetrate the soil, and mulch helps retain moisture.
If you have any comments or ideas for water-wise gardening, feel free to email Sagebrush.