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2021 Year In Review: Denver’s Forestry Office Plants Over 1,300 Trees

Lexi Brewer, Urban Forestry Operations Assistant, City and County of Denver

This past year was a busy one for Denver’s Office of the City Forester, as we provided free trees, education and resources to the community. Not only did we continue educating and enlisting the help of Denver residents to identify, treat and replace ash trees as part of our Emerald Ash Borer (EAB) prevention efforts, our work extended even further into the community as we implemented additional programs available to residents like planting free trees, the GAP tree removal and replacement plan and the Forestry Neighborhood Initiative in southwest Denver.

Read on for a recap of what we accomplished this year and how you can apply to receive a free tree in 2022.  

2021 by the numbers

Collection of stats for 2021 regarding tree services in Denver
Council District# of trees planted
City and County of Denver 2015 Council Districts and Current Precinct Boundaries

Why we plant trees in Denver

As part of the Be A Smart Ash campaign, we’ve been focused on replacing ash trees as a defense against EAB. Since 1 in 6 trees in Denver is an ash, when EAB is discovered here, it will leave gaps in our beautiful but fragile tree canopy. Therefore, we’ve been proactively combatting these inevitable gaps with the addition of new and diverse tree species.

In addition to defending against EAB, trees are important for the health of Denver’s residents, particularly in the summer. Trees cool and clean the air, provide shade and slow down rainfall. In fact, American Forests estimates that nationwide, city trees prevent approximately 1,200 heat-related deaths and countless heat-related illnesses annually. Learn more from Denver City Forester Mike Swanson about how trees combat extreme heat in Denver’s historically underserved neighborhoods.

Why the need for target neighborhoods

Denver’s Office of the City Forester works with community partners and researchers to prioritize areas of the city that could benefit the most from free tree services. Learn more about how we prioritize tree planting areas in neighborhoods across the city depending on canopy cover and household income.

Where to apply for free trees in 2022

Tree plantings, removals and prunes this year were all part of three different programs that together served our Denver community. Learn more about these programs and how you can access their services in 2022:

  • Free Trees Program: Since the launch of the Be A Smart Ash program, the Office of the City Forester has planted more than 10,000 free trees for Denver property owners in the public right-of-way. It’s easy to apply for a free tree online and if you qualify, you’ll receive tree planting support and instructions on how to care for your tree.
  • GAP Program: The Ash Tree GAP Removal & Replacement Program removes and replaces smaller, poor-condition ash trees in the public right-of-way throughout the city. In 2021, 227 trees were removed, and 165 trees were planted as part of the GAP Program.
  • Forestry Neighborhood Initiative: The Denver Forestry Neighborhood Initiative focuses on pruning or removing trees that pose a risk to public safety, as well as planting new trees when space allows. In 2021, this initiative oversaw the planting of 208 trees, as well as the removal of 110 trees, 13 tree prunings, 2 stump grinds and the watering of 167 trees. Property owners who qualify for a free tree or for tree maintenance will receive a letter and a postcard in the mail with information on which service(s) they qualify for and how to claim them. However, every property owner in Denver is eligible for a free tree if they think they have space in their public right-of-way.

We look forward to another year of partnering with our Denver community to protect our tree canopy and improve the health and wellness of residents through trees! For more information about any of these programs, email or call the Denver Office of the City Forester at 720-913-0651.

How to Be a Smart Ash | An Inside Look into Denver’s Tree Planting Program

Lexi Brewer, Urban Forestry Operations Assistant, City and County of Denver

As an Operations Assistant of Denver’s Office of the City Forester and a member of the Be a Smart Ash (BASA) team, I have loved being a part of a program that gives away free trees to Denver residents. But a lot of behind-the-scenes work happens to make our streets and neighborhoods green and shaded. In this blog post, I’ll describe our program and how you can help us grow Denver’s urban forest.

Why Plant Trees?

Tree planting is just one part of our BASA program. BASA started in 2016 as a holistic way to stop the spread of Emerald Ash Borer (EAB) by making our urban forest as resilient as possible. The EAB is a non-native insect that targets Ash trees (Fraxinus genus). The larvae of EAB burrow under the bark of the tree, which eventually prevents the tree from being able to transport the necessary nutrients between its leaves and roots for survival, ultimately killing the tree. In Denver, this pest will have devastating consequences, as approximately one in six of all of our trees are ash trees. To reduce and slow the impacts of EAB, our BASA program 1) treats existing ash trees with pesticide, hoping to increase their resistance to EAB, and 2) plants new, diverse trees that will help to fill the holes in the canopy after the death of any ash trees. Planting for diversity will also increase the resistance of our canopy to any potential future pests. Here’s how our planting program works:

Step 1: Spread the word!

Our BASA program is an “opt-in” program, which means that homeowners have to hear about the program and apply either online or with a mail-in postcard. We rely on neighbors and community partners to spread the word about our program and increase the number of people who apply – which will increase the total number of trees that we’re able to plant!

Step 2: Choose where to plant

First, we have to understand which areas of the city could benefit the most from our free tree service. To do this we work with community partners and researchers to create and analyze the data that we need. We prioritize our target planting areas based on lowest canopy cover and lowest annual household income per neighborhood, trying to service first those who could benefit the most from free trees.

In this video, one of our partners, Sylvia Leon Guerrero, discusses the benefits of trees, and how her research used GIS mapping to locate the areas of the city where trees could increase walkability and have other tremendous community benefits.

To determine exactly where we should plant the tree(s) on each property, a member of our staff goes out to the property of the homeowner who made the request. We try to plant as many trees as possible onto a site, being sure to comply with the siting requirements of the city (see below). We also look around and make a species recommendation based on the surrounding trees, trying to increase the species diversity on each street as much as possible. We’ll also note the site conditions in order to recommend a tree that will have the highest chance of survival in the area. We always email the homeowner these recommendations and work with them to provide a species that they like.

Step 3: Plant the tree & ongoing care

After the tree placement and species have been approved by the homeowner, we then use contractors to drop off and plant the trees. From there, our work is done; however, the on-going care of the tree is critical to its survival. We depend on the homeowners to water and care for their tree. Proper watering includes watering with a hose two to three times per week in the summer, at least ten gallons each time (15 to 20 minutes) and two times per week throughout the winter when the soil is dry. We’re happy to answer any care questions that anyone has at With proper care, each tree brings us one step closer to a more beautiful, resilient, urban forest!

Find out if you qualify for a free tree and learn more through exploring our website.