BY SARA WILLIAMS
A friend fondly remembers the gentle soaking effect of the “three-day rains” of his younger years. Another one talks of climate change: milder winters are okay, but the lack of precipitation is worrying. In a summer like this, I think of the lyrics of Malvina Reynold’s song, “What have they done to the rain?” as sung by Joan Baez.
Municipal and RM water rates have climbed and we seem to have needed to irrigate more than usual this summer. As gardeners, when nature does not provide, our goal is to satisfy the needs of our plants without wasting water. Most fruit, vegetable and ornamental plantings require about an inch of water per week to grow well – more perhaps when the temperatures climb past 30°C. Well-established drought-tolerant perennials, trees and shrubs can tolerate less than that.
The way we water makes a difference. It’s much better to water deeply (15-20 cm/6-8 inches down) and thoroughly once a week than it is to wet the soil only an inch or two deep daily. Direct water to the soil for root absorption and uptake, not to the leaves. Water at the base of the plant deeply and thoroughly, to the depth of the root system and a bit below, to encourage deeper rooting. Frequent shallow watering confines roots to the upper level of the soil, leaving plants with shallow roots and more prone to rapid drying between watering, especially during a drought.
The ideal way to provide water is through drip irrigation. This system applies water slowly and under low pressure to the root zone of each plant, maintaining near-optimal soil moisture levels. The drip hose or tubing can be flat or round with openings or drip emitters regularly spaced along its length. Soaker hose (aka porous pipes, weeping hose) has similar benefits. This type of hose literally weep along its entire length. Both systems can be used in straight or gently curving rows.
Almost all of the water is delivered to the root system. Easy and relatively inexpensive to install, drip and soaker irrigation works well for fruit and vegetables (but not for lawns or flower or shrub borders). Little water is lost to evaporation or “non-target” areas such as sidewalks and driveways. Disease is greatly reduced because the foliage remains dry and soil-borne disease organisms are not splashed onto your plants.
Applying mulch on top of the irrigation hose is a further and excellent way to conserve water. Water evaporates from a mulched surface much more slowly than from bare soil. Ensure that the mulch layer is at least 4 inches deep for maximum efficiency. A shallow mulch layer will allow evaporation (nor will it control weeds). For permanent plantings, slightly chopped post peelings are ideal. Post peelings are what are scrapped off pine, spruce, and aspen on their way to becoming fence posts. They are readily available from garden centres and landscape contractors. In vegetable and fruit gardens, use weed free straw or a layer of herbicide-free grass clippings.
When you irrigate is also important. Less water is lost to evaporation if you water early in the morning when there is less wind and the temperature is cooler. Watering early in the morning also ensures that the foliage of your plants will have time to dry. Many of the diseases that attack our plants multiply more quickly on wet foliage. (It’s also important not to work among your plants when the foliage is wet or YOU may be the one spreading disease.)
Another way to conserve water is to invest in a timer that attaches to your outdoor faucet. This is especially important if you may be at work or simply forget when it’s time to turn it off.
Sara is the author of numerous gardening books, among them the revised Creating the Prairie Xeriscape. And with Hugh Skinner: Gardening Naturally – A Chemical-free Handbook for the Prairies; Trees and Shrubs for the Prairies, and Groundcovers & Vines for the Prairies. Expect Fruit for Northern Gardens with Bob Bors in November, 2017.
This column is provided courtesy of the Saskatchewan Perennial Society (SPS; www.saskperennial.ca; email@example.com; www.facebook.com/saskperennial). Check out our Bulletin Board or Calendar for upcoming garden information sessions, workshops, tours and other events. Got growing questions? Gardenline is here to help! Email firstname.lastname@example.org with your questions or call Helen at 306-966-5865.