Denver Ash Tree Removal and Replacement

  • July 28, 2020

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

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

  • July 18, 2020

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

  • June 1, 2020

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

  • May 27, 2020

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

  • January 29, 2020

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

  • October 14, 2019

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

  • October 2, 2019

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.

Take Advantage of the Fall Color Change

  • September 23, 2019

As pumpkin spice lattes make their debut at our local coffee shops, so do the colors of fall. The leaves of trees in our parks and backyards are beginning to change from green to yellow, purple and plum – a clear sign that winter will soon be here. 

Ash leaves

Take advantage of these vibrant signs and Be A Smart Ash.  
With the Emerald Ash Borer confirmed in the City of Westminster, directly neighboring the City of Denver to the west, now’s the time to Be A Smart Ash. Use the vibrant fall color change as your guide and get outside; look for the most colorful leaves, then use these telltale identifiers to confirm you’ve found an Ash: 

  • Compound leaves: A simple leaf is defined as a single leaf that has a bud at the base of the leaf stem. Conversely, a compound leaf (the sort you’re looking for) is defined as having more than one leaflet per leaf connecting to a stem that has a bud at its base. Ash tree leaves typically have 5-9 leaflets per leaf. 
  • Opposite branching: By opposite branching, we mean the branches protruding from tree limbs have a mate protruding from the exact opposite side of the same limb. Only ash, maple, dogwood and horse chestnut trees have opposite branching. 
  • Diamond-pattern bark: While this identification method may not be as helpful when it comes to young ash trees (they typically have smoother bark), the bark on more advanced ash trees tends to have distinct diamond patterns. 

Once you’ve confirmed the tree is an Ash tree, make sure you don’t see any pesky green bugs around, or any wavy trail lines or d-shaped holes in the trunk. Multiple visuals can be found here. Hopefully, the tree is healthy, in which case there are multiple options to help keep it that way. 

If the tree is on public property, look for a tag that says “This Ash Is Covered” to know it’s been treated by the City Forestry Department. More information on the city’s treatment and replacement plan can be found at BeASmartAsh.org. If the tree is on your personal property, check out your next steps here. 

Think you might have an EAB infestation? Take a lot of pictures and contact the City Forester at forestry@denvergov.org or 720.913.0651. 

Find the Smart Ash Superhero Around Town

  • August 28, 2019
Fighting Emerald Ash Borer

The Smart Ash Superhero is making the rounds to local libraries, recreation centers and public spaces to introduce more Denverites to the Emerald Ash Borer (EAB) and ways to Be A Smart Ash. Be on the lookout for the Smart Ash display and let us know where you see him by tagging @BeASmartAsh or using the hashtags #EAB and #BeASmartAsh on Twitter.

Join our effort to save Denver’s ash trees by talking to your neighbors, friends and co-workers about EAB and encourage people to visit BeASmartAsh.org for more information.