Waterwise Gardening
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What is waterwise gardening?
Waterwise gardening is not synonymous with xeriscaping, which is the term used for landscaping in areas that have extended periods of drought and dry weather. Waterwise gardening is a more appropriate description for gardening that incorporates the collection and storage of rainwater, the improvement of soil health, the establishment of proper maintenance techniques and the selection of suitable plant species to create healthy, beautiful gardens.
Collection and storage of rainwater
- As rain falls onto city streets, it quickly flows along curbs and gutters into the storm sewers. By capturing and holding the rain, water can seep slowly downward through the soil to be drawn up by the root systems of plants.
- Rain Barrels - a rain barrel can be used to collect rainwater from roofs as an irrigation source for gardens in periods of dry weather rather than drawing on the municipal reservoirs.
- Contour the land to slow the speed of runoff. Excellent examples are the terracing of hills or slopes and the creation of roadside swales.
- Plant in Layers - layered vegetation intercepts a greater amount of rainfall than a single layer, such as lawn. Plant a diversity of groundcovers, shrubs and trees.
- Permeable Paving: Standard paving systems are usually placed on a layer of sand, which is impervious to the movement of water. Permeable paving is set on coarse gravel, allowing water to seep through the larger air spaces and into the soil.
Soil health
- Composting builds up organic matter in soil, thereby increasing its ability to retain water. By composting lawn clippings, leaves and other green waste, important nutrients, minerals, bacteria and microorganisms are recycled into the soil.
- Mulching protects soil from drying out, prevents the loss of nutrients through leaching, and inhibits the growth of annual weeds.
- Mulches (leaves, straw) should always be applied when the soil is moist as they keep the soil temperature and moisture availability constant at the time of application. Green manures, such as winter rye, grown as a cover crop during winter prevent loss of nutrients through leaching and are dug under in spring to provide a source of nitrogen for plants.
- Soaker hoses and drip irrigation direct water to plant roots and reduce the loss of water through excessive evaporation by releasing water at or below soil grade.
- Water sparingly - roots that have to search for water grow deeply, which helps them through extended periods of drought. Plants that are adapted to dry summers do not need to be watered during dry weather once their root systems are established.
Plant selection
Waterwise gardening is responsive to the conditions throughout the year and uses plants that thrive in periods of both inundation and drought. Select plants that prefer acidic soil conditions, resist root rot from persistent winter rains, and can tolerate dry summer weather.
Native or indigenous plants, which are uniquely adapted to both our wet winters and dry summers, have little dependence on supplemental water during dry weather. They also express the ecology of your region.
Maintenance techniques
Proper planning can reduce the amount of time and effort expended on tending and watering gardens. Maintain a regular schedule of care, and plant thickly to create shade and to smother the growth of weeds. Restrict the amount of time controlling plants that aggressively compete for light, moisture and nutrients by using plants in associations that co-exist harmoniously. The low maintenance waterwise garden requires less water, has stronger plants and benefits from improved soil.
The principles of waterwise gardening respond to local and regional conditions of climate and weather patterns, rainfall and topography.. By observing the landscape and working with it more sensitively, a deeper awareness for the natural processes that shape our surroundings develops. Not only do we create an improved environment for our plants but also a healthier environment shared by everyone.
Tips for creating a water-saving garden
- Group together plants with similar water requirements - Some plants need more water than others. By grouping plants with similar water requirements, you can help to prevent over- or under-watering individual plants. It can also simplify the design of a watering system.
- Choose plants with adaptations that make them natural water conservers - In general, plants with hairy, succulent, wax-coated leaves or with fine, stiff foliage (sclerophyllus) are adapted to growing in dry environments. Grey-or silver-foliaged plants are also usually suited to dry conditions.
- Apply a layer of mulch annually to help minimize water-loss from the soil - Mulch improves the long-term water-holding capacity of the soil and also restricts weed growth that may compete with plants for water. It should be applied in layers from 50-75mm thick.
- Mulch that is too thick can prevent rainfall and or irrigation from reaching the soil.
- Consider replacing part or all of a lawn with groundcover or change to warm-season grasses - Lawns can consume up to 90 percent of water in your garden. Warm-season grasses such as Buffalo, Couch or Kikuyu use water more efficiently and display *drought tolerance.
- These warm-season grasses can use up to 30% less water than cool-season species such as Ryegrass.
- Water deeply between the evening and early morning (if it has not rained) - This is when evaporation from soil and transpiration from plants is at its lowest. Watering deeply provides a larger 'reservoir' of water in the soil and also encourages the development of deep root systems that are more drought resistant. About 10mm (sandy soils) to 30 mm (loamy soils) of water should be applied to wet the soil to a suitable depth
- Get to know your garden and its water needs - Conditions within a garden can vary dramatically. There might be cool, shady areas or hot, dry areas; sections with well-drained soils or boggy soils; sloped or flat areas. Take advantage of this by choosing plants that are suited to the 'local' conditions or microclimates of your garden.
- Understand the performance of your irrigation system or sprinklers - There is more to watering your plants than just turning on a tap or setting a timer. A well-designed irrigation system will apply water uniformly and at the correct precipitation rate. High watering rates can result in runoff rather than infiltrating the soil. Check the uniformity and application rate by using a number of catch-cans (pet food tins) spaced evenly between sprinkler heads. Measure depth of water in tins (in mm) after watering .For many soils, the precipitation rate should be less than 10mm per hour. If this is being exceeded, cycle your irrigation by operating for short periods with time for soaking allowed in between. Significant variation of water depths between the catch-cans can suggest poor efficiency. Consider changing sprinkler types and or spacing. The watering diameter of sprinklers should reach each other, or what is termed 'head to head' spacing.
- Good maintenance keeps a dry garden in great condition - Regularly check for pests and diseases, and keep your garden weed free.
- Ensure that your sprinkler system is operating efficiently to avoid wasting water.
- Improve your soil - In new garden beds, incorporate about 40 mm of well-composted, fine organic matter in the top 200 mm of the soil profile. This should improve the water-holding capacity of the soil. For established gardens, the regular application of mulch will also improve water-holding capacity by gradually increasing the organic content of the soil.
SOURCE: VanDeusen Botanical Garden
www.city.vancouver.bc.ca/parks/parks/vandusen/website/index.htm