Planting trees can help cool your home and patio

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During last month’s intense heat, were you laying awake at night because you didn’t have an air conditioner? How about planting one?

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Planting the right tree in the right location can make a huge difference in helping to cool your home and patio. Depending on the size of the tree, it can be the equivalent of four air conditioners working eight hours a day. It will also benefit the overall environment in many ways, from cooling the air and sequestering carbon to helping collect pollution and aiding birds and other wildlife.

I’m well aware of all the potential challenges in smaller spaces, especially with height restrictions and neighbours, but there are a myriad of tree selections available today that can minimize these issues. Once established, these newer varieties are more heat and drought tolerant, and they come in all sizes and shapes to fit today’s urban realities.

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My go-to-person for advice on trees is Nancy Buley, marketing director for J. Frank Schmidt & Son Co., a nursery in Oregon. This outstanding nursery is well-known for growing quality trees and for introducing many new varieties from around the world that are more heat, drought and cold tolerant, and able to withstand changing climate conditions. Many North American cities benefit from their new tree selections for urban planting.

Buley has a passion for trees. Incredibly knowledgeable, she is acutely aware of the many issues involving them, especially about their continuing care and maintenance.

It takes two years for a new tree to become established, and it all begins with proper planting, says Buley. For a long, productive life, trees need a sufficient planting area with quality soil that allows the roots to go deep to secure moisture when water is scarce during hot summers.

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Here on the West Coast, the planting area needs to be well-draining in order to deal with heavy winter rains, yet also able to hold moisture through long periods of summer heat and drought.

Proper watering during warm spells is critical. The minimum amount of water needed for an established tree is 15 gallons per week. Infrequent, but slow, deep watering, is the way to go. Summer isn’t a great time to plant because of the stress very warm weather can put on a new tree. It would be better to wait until late August or early September.

Irrigation systems set up for surface watering aren’t the best option because they tend to draw surface roots up. It’s important to get water down deep to encourage the roots to grow down deep.

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In tight space locations, smaller-growing trees (up to nine metres) are the most practical and efficient. Drought-tolerant varieties of ornamental flowering crab apples, cherries and some dogwoods are ideal. Disease-resistant crab apples, like Malus Red Jewel, Prairifire, Royal Raindrops and many others, grow about nine-metres tall and 4 1/2-m wide. They all have attractive flowers and foliage and some, like Red Jewel, produce winter fruit.

Kousa dogwoods, once established, have great drought tolerance and provide both shade and privacy. They also flower and have nice fall colour. Buley mentioned the newer variety, Cornus Scarlet Fire, as being particularly beautiful with its deep-pink-to-fuchsia blossoms. During this recent extreme hot spell, I noted that another new variety, C. Summer Fun, with its variegated foliage, stood up very well. Both varieties grow about 5 1/2-m tall and 4 1/2-m wide.

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The flowering cherries planted around Vancouver also stand up very well, even when growing in dry roadside plantings. They, too, have great drought tolerance. Probably the most well-known variety is Prunus Kwanzan, which has double, dark-pink flowers and grows about nine-metres tall with a six-metre spread. There is a wide selection of other great varieties, including P. Autumnalis Rosea, which blooms from late winter into spring. The trend, however, is toward more narrow and compact varieties, such as P. Amanogawa, P. sargentii Columnaris and J.F. Schmidt’s introductions, P. First Blush and P. Pink Myst, which grow in the range of nine-metres tall and 3 1/2-m wide.

Columnar maples, like Acer rubrum, A.r. Armstrong and A.r. Bowhall, have become preferred choices in many cities because of their narrower habit. Buley mentioned a few that are also more drought tolerant, such as A.r. Red Rocket and Schmidt’s introduction, A. Armstrong Gold. Most of these varieties reach about 10 1/2 m to 12 m in height and 4 1/2 m in width.

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Of the larger, brilliantly red-coloured maples, Buley highly recommends a sugar maple called Flashfire for its great heat and drought tolerance, as well as their Acer rubrum Redpointe. Both grow in the range of 12 m tall and nine-metres wide. If these dimensions are too large, they can all be pruned to conform to individual site conditions.

One of the most resilient maples is Acer griseum or peeling bark maple. It’s a four-season tree with stunning red peeling bark all winter and fabulous red fall foliage. Growing about 7 1/2-m tall and six-metres wide, it’s one of the great small shade trees.

For a narrow shade tree, Buley says elegant hornbeams are still very popular. They have good heat and drought tolerance and grow about 10 1/2-m tall and 4 1/2-m wide. Carpinus Frans Fontaine is the most well-known, and according to Buley, C. Rising Fire has particularly beautiful red fall colour.

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Parrotias are some of today’s ‘hot’ trees. Growing in the range of 7 1/2-m to 8 1/2-m tall and 3 1/2-m to four-metres wide, these heat-and-drought-tolerant small shade trees have stunning fall colour and unusual red stamens in February. Buley recommended P. persica Persian Spire, Ruby Vase and Vanessa as three of the best cultivars.

Hardy Ivory Silk Japanese tree lilac is one of the truly great smaller shade trees. Growing only six metres in height and about 4 1/2-m wide, it’s very heat and drought tolerant and can be widely grown. This late, white-flowering lilac adds great June colour.

Buley was very high on Japanese snowbells, and her favourite is Styrax japonicus Evening Light, with its rich, dark foliage and white flowers. She also mentioned that Snowcone is a very elegant tree that grows about 7 1/2-m tall and six-metres wide with masses of white flowers hanging like little bells.

These are a few of the many trees that will help cool down your home during hot summers. Just having the chance to sit in their shade makes them a valuable asset. It seems we may be experiencing more extreme weather, and the trees I’ve written about here are more tolerant of these conditions.