When it comes to growing a cooler backyard, for once I’m not talking about edgy, eco garden design trends. As southwestern Ontario continues its record-breaking heat wave, gardening is now all about the temperature. And since last month (July, 2016) was the hottest month around the world in recorded history, I don’t think we’re alone in thinking about heat and how to avoid it. City and suburban dwellers are the most affected since “downtown metropolitan areas can absorb and store twice the amount of heat compared to their rural surrounding during the daytime,” according to the US Environmental Protection Agency. Here are 10 ideas for taking the heat off your little patch of paradise.
Any building, gazebo or umbrella can provide cooling shade but trees, shrubs and other plants are better at creating cooler outdoor areas. That’s because plants don’t just block the sun. They emit water through their leaves in a process called transpiration. This water then evaporates, cooling the air (because heat is required to convert water from a liquid to a gas). Moisture that evaporates from the soil around trees and shrubs and from raindrops that have landed on their leaves also help cool the surrounding air. The whole process, called evapotranspiration, when harnessed in combination with shading, can effectively reduce the heat in your backyard.
Make leaves work for you: Deciduous trees and shrubs can help regulate how much your home is exposed to sun. In the summer, the leaves provide shade, decreasing your home’s sun exposure. In fact, the combined shade produced by leaves and branches can reduce the amount of solar radiation by 70 to 90 percent. In the winter, their bare branches let the sun shine through when you want heat from the sun the most.
Mind the gap: Don’t plant evergreen trees and shrubs right up against the walls of your home. Calculate the width of your plant at maturity and then add an extra foot of space. That gap creates a cushion of calm air that helps insulate your home in winter and summer.
But vines can stay close: A study cited by the USEPA found that vines can significantly reduce the temperatures absorbed and reflected by walls. When you have very little space for your garden, vines can be your new best friends. If you only have a narrow space between your home and your property line, you can still reap the benefits of cooling shade and evapotranspiration by growing a leafy vine up a free-standing panel of trellis.
Plant strategically: If you have the room, plant large groupings of taller trees in the south and west portions of your garden to cut down on sun exposure in summer.
Reduce heat from your driveway:
- Planting trees or tall shrubs to cast a shadow on your paved driveway will reduced the reflected heat from the asphalt.
- If you’re installing a new driveway, consider using pavers rather than a solid surface. The spaces between the pavers allows evapotranspiration from the soil and plants to cool the area.
- If you’re set on a solid paved driveway, keep in mind that the lighter coloured your pavement, the lower the temperature of the pavement during the dog days of summer. This is because lighter colours reflect the sun more efficiently.
- If you’re looking to resurface your driveway, consider topping the concrete or asphalt with a lighter coloured aggregate. Asphalt can be covered with sealcoats that promise higher reflectivity. Both will help protect your driveway’s surface from absorbing heat.
Lighten up your patio: Lighter coloured ground surface materials, whether pavers or gravel, will effectively reduce the overall temperature in your backyard by reflecting rather than absorbing the sun’s rays. When it comes to furnishing your patio, using lighter coloured woods and fabrics also help make for a cooler backyard.