During this hot summer, we all appreciate the cooling shade of trees. Some studies have shown that shade trees can cool the surrounding air by up to 4.5 degrees, or surfaces by up to 15 degrees. Another study showed that trees planted to block the afternoon sun reduced energy consumption (due to air conditioning) by up to 31%.
In contrast, hard surfaces such as concrete and asphalt can reflect sunlight and make the surrounding area hotter. This effect has not gone unnoticed by our local government. The Hawaiian Electric Co. has long advocated for planting shade trees in the yard. Its brochure “Planting the Right Tree in the Right Place” gives advice on how to maximize the cooling effect of trees while minimizing risks to infrastructure. You can find it online at hawaiianelectric.com, click on Products &Services, then click on Energy Savings Toolkits.
Honolulu’s Mayor Kirk Caldwell has announced a commitment to plant 100,000 trees by 2025 and increase tree canopy cover to 35% from 25% by 2035.
Trees provide more than just shade. They can also be very useful. Hawaiians, Pacific Islanders and people from around the world have always utilized trees for fruit, edible shoots and leaves, wood, fiber, foliage, flowers, animal feed and other benefits. The classic Hawaii backyard features a fruit tree such as mango, lychee or avocado, as well as citrus or more exotic fruits.
Pamela Hinsdale, a University of Hawaii master gardener, grows native ohia lehua and alahee as well as other useful trees and shrubs in her East Honolulu garden. As a lei maker, she loves the liko from her ohia. The honeybees from her hives go crazy when her alahee and other native plants are in bloom. All the plants in her garden are both beautiful and useful in some way.
Learn more about trees at the Oahu Urban Garden Center in Pearl City on Saturday from 8:30 to 11:30 a.m. for the Second Saturday at the Garden event.
There will be a guided tour of the fruit orchard, where you can see a wide diversity of tropical fruits. Besides many varieties of our favorites such as mango, lychee and guava, see more exotic fruit trees such as jaboticaba and egg fruit. The tour runs from 8:45 to 10 a.m.; the $10 fee includes a tasting of available fruits and a drawing for grafted mango (Zillate variety), fig, miracle berry, jaboticaba and Meyer lemon plants.
At 10 a.m., members of the Aloha Arborist Association will lead a workshop on pruning young trees. Learn from certified arborists how to properly care for and shape your tree from the beginning. The workshop costs $5, payable in cash at the door.
To register for the tour
or workshop, call 453-6050
to reserve a spot. For more information, go to
ctahr.hawaii.edu/ougc.
The garden will be open at this time, so bring your family and friends to stroll the gardens and talk to UH Master Gardeners.
Kalani Matsumura is a junior extension agent with the University of Hawaii’s College of Tropical Agriculture and Human Resources and coordinates the UH Master Gardener Program on Oahu.
