Arbor Month

April is Arbor Month!

Arbor Day is America’s National Tree Holiday, observed on the last Friday of April to celebrate the role of trees in our lives and to promote tree planting and care. This year marks the 150th Anniversary of National Arbor Day. For the second year in a row, Governor Brown has proclaimed the entire month of April as Oregon Arbor Month, and Mayor Buck proclaimed April Lake Oswego Arbor Month, too. Click here to read the City’s proclamation.

For 33 years, the City of Lake Oswego has earned Tree City USA (TCUSA) recognition from the National Arbor Day Foundation. The TCUSA program recognizes cities for demonstrating a strong commitment to managing and caring for trees. Cities earn TCUSA status by meeting four standards: maintaining a tree board (the Parks, Recreation and Natural Resources Advisory Board), having a tree ordinance, spending a minimum $2 per capita on urban forest management, and proclaiming and celebrating Arbor Day annually. There are currently 69 TCUSA cities across Oregon. Visit to learn more.

Explore the links below to find fun ways to celebrate trees during Arbor Month and throughout the year, and be sure to check out the 2022 Urban & Community Forestry Newsletter.

Celebrate Arbor Month

Saturday, April 2, 10 a.m. to 4 p.m., Tryon Creek State Natural Area, 11321 S. Terwilliger Boulevard

Join Friends of Tryon Creek to celebrate the return of the Trillium, an early season perennial native to our local forests, at the 42nd Annual Tryon Creek Trillium Festival. In addition to the native plant sale, activities for the whole family include interactive forest habitat educational stations, guided and self-led Backyard Habitat Hikes, natural area and watershed educational displays, and new this year – homeowner wildfire prevention and living botanical tabletop gardens. Be sure to stop by the Lake Oswego Parks Stewardship exhibit to learn about family friendly habitat restoration opportunities led by Parks Friends Groups and get a Stewardship Gnome tattoo and sticker!

Saturday, April 9, 10 a.m. to 12 p.m., Foothills Park Pavilion, 199 Foothills Road

Understand why, what, and how to prune to develop healthy, strong, and attractive trees and shrubs. Explore pruning types, proper cutting tools and techniques, and tree responses to pruning. This workshop is led by ISA Board Certified Master Arborist Damon Schrosk of Treecology, Inc. Pre-registration is required and capacity is limited to 30 Lake Oswego residents. Please click here to register for free. 

Sunday, April 10, 1 to 3 p.m., Park on Hemlock Street or Hallinan Street (Hallinan Woods is by the Hallinan Elementary School field, follow the paved trail into the woods)         

Join Friends of Hallinan Heights Woods to free trees from invasive ivy and help restore the native habitat. Family Friendly. No experience needed. Dress for weather and wear closed toe shoes. Bring gloves and water to drink. Restrooms are not available. To register, contact Christy Clark at 916-261-1514 or Contact Babs Hamachek, Stewardship Coordinator, at 503-534-5697 or to learn more about volunteer opportunities to help restore and enhance the City’s natural area parks.

Monday, April 12, 11 a.m. to 1 p.m., Indoor Presentation and Outdoor Demonstration at the Lake Oswego Maintenance Center, 17601 Pilkington Road
Saturday, April 16, 1 to 3 p.m., Outdoor Demonstration and Practice Session, George Rogers Park, 611 S. State Street (Meet near the Iron Furnace)

Oswego Lake Watershed Council has developed a tree survey tool called LOTree that anyone can access through their smartphone or tablet. Volunteers are trained on how to use the survey to collect individual tree data and help build a snapshot of the health and diversity of Lake Oswego’s urban forest. If you’d like to be trained on how to use the survey and practice data collection with other community volunteers, please attend either or both of these Arbor Month workshops! For free workshop registration and to learn more about LOTree, visit

Saturday, April 23, 10 a.m. to 2 p.m., Luscher Farm Barn, 125 Rosemont Road         

Children ages 5 to 12 are invited to spend Saturday morning at Luscher Farm, creating crafts to celebrate Arbor Month and Earth Day, partake in fun farm activities, and learn about organic gardening. Visit to enroll; $42 for LO residents, $63 for non-residents.

Sunday, April 24, 11 a.m. to 2 p.m., Lakeridge Middle School, 4700 Jean Road

The City of Lake Oswego’s Sustainability Advisory Board is partnering with the Lake Oswego School District, Lake Oswego Sustainability Network, and Oswego Lake Watershed Council to hold the first annual Lake Oswego Sustainability Resource Fair. Come learn about the work that organizations across our community are doing to advance sustainability, connect with community members who are interested in sustainability, find opportunities to participate in educational programs and volunteer with sustainability-focused organizations, and learn how you can help protect the environment, save money, and give back to your community. Kids can participate in arts and crafts and everyone can tour the new Lakeridge Middle School and its sustainable design features. Bartlett Tree Experts will be giving away tree seedlings, too!

Wednesday, April 27, 10:45 to 11:45 a.m.

Bring your preschoolers to learn what trees do to thrive and survive as we explore the woods. This nature walk is led by enthusiastic guides from Friends of Springbrook Park. Exploration buckets will be provided. Free! No registration needed. Children must be accompanied by an adult. Contact Anne Lider at 503-701-2291 or if you have questions. Park at Uplands Elementary School, 2055 Wembley Park Road (meet at the Park kiosk located below the school playground).

The wily Stewardship Gnomes, Blossom, Greenie and Oak, will hide in three natural area parks from April to October. Come out and find them, you may win a prize! Here’s what to do:

  • Find the gnomes and take a photo of you, your dog or anything by a gnome.

  • Post your gnome photos on social media using the hashtag #LOparksgnomes for a chance to win your very own garden gnome this October.

  • Need a hint? The gnomes will be hiding on trees at Hallinan Woods, River Run Natural Area and Springbrook Park during April, and they’ll make their way to Foothills Park, Iron Mt. Park and Southwood Park in May.

Visit each month for clues where the Gnomes are hiding and discover fun facts about the City’s 460-acres of natural park areas, native plants, wildlife and birds.


We learned so much about the health of Lake Oswego soil from last year’s Soil Your Undies event that Oswego Lake Watershed Council is inviting you to participate again! Get your hands dirty and put your soil to the test by taking the “Soil Your Undies” challenge. All you have to do is bury a brand-new pair of 100% cotton underwear under at least 6 inches of soil, wait 60 days, and then dig them back up. The more your undies break down while buried in the soil, the more active the biological community in your soil is. To receive a free brand new pair of undies and learn more about how you can partake in this fun soil science activity please visit


We love our trees! We love their shade, their graceful patterns against the sky and how they store carbon to combat climate change. But where would trees be without their roots? We cannot see their roots, but know they anchor the beauty towering over us.

Where does that stability come from? The soil into which the tree roots reach.

What do we know about that soil? Do we just take it for granted? It’s always there!

That soil is as important to the health of our trees as the air is to the trees making food. The air supplies the carbon for tree leaves to make the food and structural building blocks to keep the tree alive and growing. An important part of that process (known as photosynthesis) also requires water that is extracted from the soil by the tree roots. But that soil does so much more than anchor the tree and provide water—it also supplies all of the minerals and other nutrients (particularly nitrogen) trees need to live.

For many years soil scientists thought of soil as an inanimate object composed of ground up rocks. But that is only half of the story. The other half of soil is air, water and organic matter which includes a multitude of living organisms. The living, biological component of soil includes microbes, mycorrhizal fungi, insects and worms. Most of which are too small to see with the naked eye. This living component of soil is the key to healthy, fertile soil. This unseen living system breaks down the soil to supply minerals, capture nitrogen from the air, and create spaces for water and air. Without this living component, soil just doesn’t work properly.

Tree roots are an important part of this system since plants actually take some of the food they make in the form of sugars and pump it into soil to feed these organisms. This is an interactive system where the biotic components provide nutrients and plant roots provide food for these organisms. When we use pesticides and artificial fertilizers, we kill off these living organisms and destroy this interactive system. Artificial fertilizers can actually make tree roots lazy and they stop expanding and feeding the soil.

We all benefit from understanding natural systems and supporting natural processes. Get to know your dirt! Join us for Soil Your Undies activities during Arbor Month!


Team up with the Oswego Lake Watershed Council (OLWC) and your neighborhood’s Urban Forest Committee to be an urban forest hero by removing invasive ivy from your trees and property. OLWC offers tools, education and leadership. Find out more at Will you answer the call to be an LO Tree Hero? Take a photo of trees that you saved from ivy and send them our way by tagging @oswegolakewc on social media (Facebook, Instagram) and using the hashtags #LOTreeHero and #UrbanForestSuperhero. Contact OLWC Community Outreach Specialist, Allie Molen, at for more information.


Celebrate Arbor Month with a book! The Lake Oswego Public Library, located at 706 4th Street, will have tree-themed books on display all month and tree seedlings will be given away April 22-29! The Children’s Library (lower level) will have supplies on hand to create a small or large work of art using inspiration found in the trees around you. Add some wildlife and you may want to submit your work for the Arbor Month Art Contest! Open daily: 1 to 5 p.m. Sunday, 10 a.m. to 7 p.m. Monday-Thursday, and 10 a.m. to 5 p.m. Friday-Saturday.

Learn About Trees, Wildlife and The Great Outdoors

Celebrate Arbor Month with a book! Lake Oswego Public Library librarians have carefully compiled Arbor Month-themed book lists for all ages through our Pinterest accounts. For children, visit to find direct links to picture books, information books, and chapter books about trees for children. For adults, visit to find direct links to e-books, e-audiobooks, and streaming videos on nature.

Explore the related links below:

Related Links