Gardening by Judith Adam Hot enough for you? Canadian forecasters of environment and climate change predict that 2026 will be among the hottest years on record. Record-breaking heat is a frequent cause of crop loss, shrinkage of Arctic ice and snow reserves and uncontrollable wildfires. These are catastrophic regional events but, even on a smaller scale, intense summer weather can be destructive to a home garden. Locations that are vulnerable to extreme weather settling in for weeks are difficult to predict, but it is likely that most regions will catch a period of scorching heat during July and August. Plants require safe levels of exposure to heat and ultraviolet light to produce their flowers and fruits effectively. But when heat waves generate excessively high temperatures, the delivery of UV light is greatly increased, resulting in the same effect as putting flame to soft plant tissues. The intense heat also enters the soil system, stressing plant roots in the ground. Backyard vegetable patches and borders of ornamental summer annuals with no overhead tree shade are extremely vulnerable to intense ultraviolet exposure raising soil temperature and burning leaf tissues. Plants can possibly recover from two or three days of extreme UV exposure, but a week is too much and several weeks will extinguish potential recovery. Quick strategic action can make all the difference in moderating the stress on plants until heat subsides. First, prevent heat from entering the root zone by mulching all exposed soil with a two- to three-inch layer of organic materials such as shredded tree bark or small bark nuggets, leaves, grass clippings and conifer needles. The mulch will blanket the soil, lowering the temperature in the root zone and preventing moisture evaporation. Cover soil at the base of shrubs and trees, as well as surrounding the stems of plants growing in containers. Second, create shade wherever plants are growing in half- to full-day sun exposure. Plant foliage can be protected by using a white shade cloth or row cover fabric to shade the entire section. Shade-cloth fabric reflects 30% to 50% of UV rays away from plants, while allowing air and water to pass through. Low-growing vegetable and flower beds can easily be covered with low hoops supporting the shade cloth held in place by long soil staples. The very lightweight cloth can also be used for any grouping of ornamental plants or singular specimens needing protection, simply by draping it over the plant and using small rocks to hold it in place. Look for shade cloth (and hoops and soil staples) at garden centres or in garden catalogues. It comes in large sheets that can easily be cut with scissors to fit specific purposes. With summer upon us, our expectations are for another relaxed season at home and in the garden. But a warming climate and intense weather systems across Canada are demonstrating the need for quick strategies to get through weeks of intense heat. Timely intervention and simple changes in how we prepare for climate stress can sustain our favourite plants through current heat waves. Intense heat can drain life from plants in a matter of hours. But quick intervention with simple and sustaining strategies will save the garden for better weeks ahead. Gardening in the heat of summer 46 | www.snowbirds.org
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