Presented by Ewan MacKenzie, Exemplar Horticulture
September 28th, 2010
Powell River Garden Club Meeting
A crowd of approximately 90 Powell River Garden Club members thoroughly enjoyed Ewan MacKenzie's presentation of Waterwise Gardening for Powell River Garden Club on September 28th. Ewan has kindly given permission for us to publish his presentation (see below) on our blog.
Waterwise Gardening for Powell River Garden Club
Between climate change and watering restrictions waterwise gardening is becoming more popular. Waterwise gardening is making informed decisions on water usage based on climate, seasonal watering restrictions and/or water availability, and personal environmental watering goals.
The first step of waterwise gardening is to set a personal water usage goal. Then review your garden for exposure to sun and shade as well as wind, and natural soil moisture levels. Once you have done that you can work with the given zones and plant accordingly. You can change the landscape to retain moisture, plant shade trees, hedges and windbreaks to reduce water loss. Review the soil structure, which may vary in different parts of your garden, then amend it based on its requirements. It may need to be amended with organic matter to help retain moisture. Deep cultivation promotes deep rooting.
Traditional lawns are very thirsty and require high maintenance, so carefully consider the percent of your garden you want to assign to lawn. Alternatively, go with a more drought tolerant seed mix. A healthy well-maintained lawn is more drought tolerant. Irrigate lawns wisely, less frequently, but deeply, twice a week should be enough. An alternative is not to water it and let your lawn turn a golden brown in the summer - it's not dead, it's dormant and will green up surprisingly quickly when you get some rain.
If you are going to irrigate be wise about it and go with low volume drip irrigation. Regular sprinklers are only 65% effective, as 35% is lost to evaporation or run off. Low volume drip irrigation is 95% effective due to water being delivered directly to where it's required. Use of irrigation timers or computers can be handy where you have watering restrictions that happen at inconvenient times, like early in the morning or late in the evening, also solves the problem of getting someone to water for you when you are on vacation. Also, it is recommended to have an irrigation timer that has an incorporated rain sensor. Water butts or barrels can be placed on downspouts to collect water during rainy spells.
Your planting plan should first consider big trees and shrubs which can offer shade and act as a windbreak. Then you should group plants with similar watering requirements into specific zones. This can either be done using your natural water zones in your garden, or you can create your own water needs groupings. Within those groupings consider complimentary plant groupings, for colour and contrast.
Drought tolerant plants do need watering until they are established. For vest results, plant in spring or fall when there is enough natural moisture and temperatures are not too extreme. Keep all plants adequately watered until well established. Depending on the plant this may take anywhere from several months to several years.
Once planting is done it is a good time to lay down low volume drip irrigation, which can now be covered in mulch. Mulch is a very important part of waterwise gardening as it reduces water evaporation from the soil surface and also suppresses water thirsty weeds. A 3-inch layer of mulch is ideal and if it is an organic mulch that decomposes it should be topped up each year with an inch of fresh mulch. Inorganic mulches can look good but be aware that they usually absorb a lot of heat and are not as effective at reducing moisture loss as organic mulches. please be careful to avoid choking newly planted plants with mulch. Mulch should be tapered down towards the crown of the plant.
Useful websites: www.metrovancouver.org/about/publications/Publications/WaterwiseGardening.pdf
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High and Dry, Nold, Robert