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Water, Trees, Life Livestream: Fall Colors & Leaf Bags

Welcome to the Water, Trees, Life livestream!

Grab your family and friends for this interactive, educational show from the Be A Smart Ash team. Each livestream brings the natural world of Denver into the comfort and safety of your living room. The third episode in the series debuted on Friday, October 16 at 11 AM on the Denver Parks & Recreation Facebook page, but you can watch the episode in its entirety above.

In Episode 3, leaf-peeping season is in full swing, and we want to help you enjoy it. We discuss the importance of winter watering for your trees, explore the beautiful fall colors and provide tips about how to protect your ash trees from Emerald Ash Borer. We also explain how you can turn your fall leaves into EcoGro compost, available locally from Ace Hardware. See previous episodes here.

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.

Denver Ash Tree Removal and Replacement

Knowing you Denverites are likely spending more time at home and in your yards than in previous summers, we want to help you learn more about how you can help protect and preserve Denver’s urban canopy and specifically, what the City Forestry team is doing this year to help combat a relentless ash tree insect.

You may be familiar with the Be A Smart Ash program, and you may have heard that the threat of Emerald Ash Borer (EAB) on 1 in 6 of Denver’s trees is imminent. The Q&A below will help explain what the City Forestry team is doing in select neighborhoods to combat EAB; i.e. removing ash trees in poor condition in your right-of-way and how they will replace that tree with a free tree – regardless of whether you have an ash tree – to help bolster and diversify our precious urban canopy. 

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Water, Trees, Life Livestream: Discover Denver’s Urban Forest

Welcome to the Water, Trees, Life livestream!

Grab your family and friends for this interactive, educational show from the Be A Smart Ash team. Each livestream brings the natural world of Denver into the comfort and safety of your living room. The second episode in the series debuted on Friday, July 17 at 11 AM on the Denver Parks & Recreation Facebook page, but you can watch the episode in its entirety above.

In Episode 2, we visited the often-overlooked 14,000 acres of Denver Mountain Parks to explore the relationship between forest ecology and Denver’s drinking water. We then took a trip back down to the city to learn about how we can plant trees to make parks more accessible. Finally, we spoke with a wildlife expert about our urban beaver population — that’s right, Denver has beavers!

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How to Protect and Preserve Denver’s Urban Canopy

Michael Swanson, City Forester, Denver Parks and Recreation, wrote about how his forestry team is taking care of ash trees located on city property (including parks) and in the public right-of-way.

Learn how you can personally contribute to the effort to protect and preserve Denver’s urban canopy here.

Water, Trees, Life

Join the forestry team from Denver Parks and Recreation as they guide us through three stories about the natural world in Denver and a discussion about how we help our urban canopy thrive.

Winterize Your Trees

The new year is in full swing and as the winter weather ebbs and flows, Denver will continue to see freezing temperatures, flurries of precipitation and snowstorms potentially as often as we see sunny, 60-degree days. We caught up with the smart folks at Denver Parks and Recreation’s forestry office to discuss the best methods for winterizing the trees in your yard. For insight and expertise on how to protect your trees from Denver’s highly variable winter months, read on.

How should a homeowner protect a tree during the winter months?
Place mulch around the base of the tree, about three to four inches from dripline to dripline, if not three to four inches. Leave a three-inch gap from the edge of the mulch to the stem of the tree. Because we have warm winter days in Denver, too, watering your tree in the winter is also essential. Flood irrigation around the tree when daytime temperatures reach 45 degrees or higher (if the drip line lacks residual snow cover). In Colorado, winter watering months are typically November to February. Regardless of the age of the tree, this advice applies across the board.

Is there an ideal timeframe that Colorado homeowners should have their trees pruned each year?
Pruning can be done at any time. The dormant season is best for pruning, especially for fruit trees, but homeowners who do their own pruning should wait until they can determine the difference between live and dead material. Always hire a professional if you’re unsure. However, American elms and any tree in the rose family (crabapples, pears, plums, cherry, apple) should be pruned during the winter months. Fruit trees should also be pruned in the winter months to avoid the spread of fire blight. Pruning maple and walnut trees during winter months is not ideal because they will bleed sap from the pruning cuts.

Should people expect a certain level of damage to their trees during the winter or can it be entirely prevented?
Winter damage can be avoided if trees are regularly watered and properly mulched. Damage can occur in what we describe as “heavy load events” – a lot of snow breaking limbs – or a quick hard freeze, especially common for conifer trees. We saw this happen recently in October 2019 because of the two freezing nights.

When discussing winter damage, the term “dieback” comes up fairly often. What is dieback?
Dieback is a condition in a plant in which branches or shoots die from the tip inward; caused by many conditions, but particularly a drought condition if they are not properly watered.

If branches break in a snowstorm, what’s the best use of those that have fallen or broken?
We advise mulching them and re-using that material in your landscaping, flower beds and even around the base of your trees by chipping material using a brush chipper. Alternatively, Denver’s Department of Transportation & Infrastructure (formerly Denver Public Works) collects a limited amount of branches. These must be no larger than four inches in diameter, and they must be cut into lengths of four feet or less, bundled and tied, and weigh no more than 50 pounds. Customers may set out up to 10 bundles of branches on their scheduled every-four-week extra trash collection. Denver residents can also drop off branches at the Cherry Creek Recycling Drop-off center.

Do you have any other tree winterizing tips?
For young trees wrap the trunks each year with tree wrap, until the bark develops furrows. This is especially important with thin-barked species such as honey locust, maple, linden and fruit trees. Starting at the base, wrap the trunk covering each turn about 30% up to the first branch union of the canopy to protect them from the intense sunlight.

Keep Leaves Out of Landfills

Once again, we’re excited to partner with our friends at Denver Public Works, Denver Recycles and Ace Hardware to give away FREE 5-packs of compostable 30-gallon paper leaf bags to help Denver residents keep leaves out of landfills!

Unlike plastic bags, these brown paper bags can be composted along with the leaves; saving time and reducing plastic waste in our landfills. This fall, Be a Smart Ash and compost your leaves.

  1. Download a coupon for free and compost-friendly leaf bags.
  2. Redeem your leaf bag coupon at an Ace Hardware store near you by printing it or showing it to a cashier. See a map of participating locations here.
  3. Fill the paper bags with your leaves.
  4. Drop off your paper leaf bags at your nearest Denver LeafDrop site.

Attack of the Zombie Trees

Halloween is upon us! Do you know what’s spooky? Zombie trees.

Zombie trees are those that are still standing upright but are dead inside from a variety of environmental factors; disease, insect infestation, improper pruning and lack of water. They might look alive but these ticking time bombs will eventually topple over, posing a real danger to both the public and your property. If you have a zombie tree, a strong wind could easily send it toppling over and cost you thousands of dollars in damages – to your yard, roof, vehicles or wherever it may land.

Symptoms of a zombie tree:

  • Bark that is decaying, missing or showing breakage
  • Loss of leaves
  • Dead and/or falling branches

“Because we have early fall snows and high winds in Colorado, Denver residents should always be mindful of the health of the trees on their property,” said Sara Davis, Urban Forestry Program Manager in the Office of the City Forester.

If you live in Denver and own property, you are responsible for:

  • Cleanup of debris from trees on private property and from trees within the public right-of-way adjacent to their property. (Limbs on the ground are considered debris. Property owners can hire any company to haul limbs away – for this type of work, the company does NOT have to be a licensed tree contractor.)
  • Pruning needs of private property trees and trees within the public right-of-way adjacent to your property.

Unfortunately, there are times when the safety of the public necessitates that the work be completed immediately and Denver Forestry cannot allow time for the property owner to find a licensed tree professional. When a tree or limb is blocking safe access to the street or right-of-way, Denver Forestry has an on-call contractor remove the limb or tree and bills the property owner for the work.

There are many tree professionals that are licensed by the Office of the City Forester who can safely remove a zombie tree from your yard, sparing you the costly expense of a fallen tree. Before you hire someone to remove your zombie tree, ask if he or she has a Colorado State Department of Agriculture tree service license.