Stories & Features

Plant a deciduous shade tree to help cool your home

Image of a home porch shaded by shade trees
BC Hydro community team member Hannah Wilson.

The right tree, in the right place, can help cut cooling costs

Hannah Wilson
For bchydro.com

As the summer heat beats down on your house and air conditioning costs go through the roof, it may be time to explore alternative cooling options.

How about planting a deciduous shade tree in your yard?

A recent poll of Team Power Smart members suggests that many British Columbians are keen on this option. So to get started, here's some go-to information on climate and tree types, along with some safety tips – including important advice around trimming only those trees whose branches are at least three metres from the nearest power line.

Plant the right tree in the right place, and you'll be set to keep cool for years to come. And by going with a deciduous tree, the leaves will drop in the fall to allow that precious sun to reach your windows during the cooler months.

"One average-sized shade tree has a cooling effect equivalent to four household air-conditioners running 12 hours a day," wrote Brian Minter, perhaps B.C.'s most well-known gardening expert, on gardeningBC.com.

The key is to select the right tree for your region, and to plant it in a place – usually on the west side of your home – that helps cool your home in the summer months.

Check your area's zone hardiness rating, and find a tree you like

BC Hydro vegetation management specialist Rene Roddick suggests picking a tree that gives you more than just shade.

"Pick something that has nice interesting leaves or flowers," says Roddick, who's in the process of doing just that for his own yard. "You want to make sure you buy a tree big enough that the wind, or even people moving in your yard, aren't going to snap. But you don't want it too big, because if it's too big, the tree will spend three years growing roots before it grows any height."

Optimal growing conditions depend largely on climate. In warmer, damp climates, such as the Lower Mainland and Vancouver Island, most deciduous trees thrive. In parts of the Interior and northern regions of B.C., a tree that will withstand a harsher climate is vital. To clarify an ideal shade tree in your part of the province, refer to this British Columbia zone hardiness map [GIF].

You can usually find the hardiness zone rating on the plant when you buy it, or you can look it up in a reference book. Keep in mind that you can select plants for your area that are in, or below, your area's rating, but not above.

If you live in a drought-susceptible area, don't fret – there's still a tree for you.

"The Gleditsia triancanthos, or honey locust, is a tough water-wise tree that grows really well in the southern Interior, like the Okanagan," says Roddick. "The Catelpa is a good one too. Same with the Linden – they grow well up there."

If you're concerned about getting enough water to a young tree, consider buying a gator bag, a slow-release watering system for newly planted trees. Timing your planting for the early fall, rather than spring or summer, may be better if you have concerns about moisture.

"During the hot dry periods of the summer, go out there once or twice a week to give the trees enough moisture to keep them alive during the drought period," says Roddick.

Roddick says to check for the mature height and spread of your new tree and don't plant under power lines. Be careful not to plant so close to your house that the roots start to mess with your drainage systems, and keep in mind the possibility of roots breaking through sidewalks or leaves clogging your gutters.

How fast will your tree grow, and will it get close to power lines?

Staying true to our BC Hydro roots, we have some safety tips to consider when planting your deciduous shade tree. Be wary of overhead power lines and ensure that your tree doesn't grow too high or wide so that it grows to within three metres of a transmission or distribution power line.

This distance is important, not only to avoid direct tree-to-power line contact, but also for pruning. Canadian Living magazine gives examples of shade trees, such as the Japanese maple, that will cap out at no more than five metres in height, so you can ensure your tree won't be a safety hazard.

While there are trees that will grow four feet or more a year, that tree may not be the right choice for your zone (or it may cause problems down the road). A reasonable expectation is that your tree grows 1.5 to 2 feet a year.

Finally – and as always – before you start digging, make sure you know what's below. Call or click BC One Call, to locate any potential underground electrical wires or drainage lines that could be a hazard while planting.

Do your research, choose your tree, take the proper safety precautions and within a few years your yard and your home will be cooler.

Hannah Wilson is a member of BC Hydro's community team.