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Say “Yes” to the Mess

Between life, work and home, we’re all busy bees these days. It seems like there is always one more thing on our never-ending list of to-dos. But when it comes to your home garden, we want to share an idea from Denver’s Office of the City Forester that will help keep your scene serene. Because keeping things pristine? That takes too much time. So, give yourself a rest and leave a little mess!

Think about the pollinators.

Flowers, fruits and leaves are great for pollinators. Having plenty of flowers and flowering trees around for pollinators is crucial to healthy pollinator populations, which are necessary for food production that we need as humans. It’s all connected.

Flowers, fruit and leaves are also good food sources and habitats for our insects and wildlife. Plus, embracing the messier side of landscaping is vital to maintaining a healthy urban ecosystem, because it helps to balance diseases and pests.

Bee resting on a branch of Linden flowers.Some trees attract bees.

In 2022 we planted this linden tree on request, as the property owner had a beehive and wanted them to have linden flowers to make their honey.

Leave some leaves.

Collecting leaves is a rite of fall. Raked piles make the cutest landing pads for our little ones and the colors somehow make the chore seem less like work and more like a nice way to get some cool crisp air in your lungs and not feel like you’re actually getting exercise too! But just say no to plastic and instead, responsibly dispose of leaves in compostable paper bags. You can get them for free from our LeafDrop program.

But don’t work too hard – try to leave a few leaves behind. Do a pass or two with your electric mower to chop up the leaves into small pieces for faster return of organic matter into the soil Creating compost from your organic food scraps and yard waste, like leaves, is a great way to make fuel for your trees, lawn and flower beds. Just add a little in when refreshing your mulch.

Besides leaves, how else do trees make an embraceable mess?

Some trees make their mess by dropping seeds, so they can adapt and reproduce the next generation. This post from our friends across the pond tells us about the five ways trees spread their seeds: the plant disperses them by gravity or force, or they spread seeds with a little help from animals, wind or water. Cleaning up after these trees hampers their hard work to survive.

As always, if you need more information, please contact Denver’s Office of the City Forester at or 720-913-0651.


Fall Tree-Planting Tips to Help Them Thrive

Leaves with autumn yellow colors of the Kentucky Coffeetree.

Regardless of what the thermometer reads, it appears that summer is coming to an end –– which means that fall will soon bring us the gift of cooler breezes, colorful leaves, and the desire to engage in all the cozy things. It’s a beautiful season to get outside in Colorado, and the perfect time to plant a tree and contribute to our urban canopy.

Fall is a great time to plant new trees!

People tend to think of spring as the time to plant trees, but the truth is, fall can be even better! The heat of summer has left behind healthy soil, ready for planting. And there are plenty of sunny days between now and the first freeze to get those roots growing strong. There is always more to learn, but we’ve narrowed it down to some of the basics here: Everything You Need to Know About Planting a New Tree.

Where should I plant my tree?

Make sure there’s room for a new tree in your public right-of-way, especially if you’re applying for a free tree. We recommend following these spacing guidelines whether you’re applying for a free tree or planting on private property. Basic where-to-plant guidelines:

  • 30 feet from the outside edge of intersecting curbs, to preserve the sight triangle
  • 35 feet from large shade trees
  • 25 feet from ornamental trees
  • 20 feet from streetlights
  • 20 feet from stop signs
  • 10 feet from edge of alleys, driveways and fire hydrants
  • 7 feet behind attached sidewalks
  • 5 feet minimum from buried electric lines and plant ornamental trees under overhead power lines
  • 5 feet minimum from water meters/pits, gas lines[MJPDCM2] , but 10’ preferred
  • Centered within tree lawns/planters

How mu(l)ch is too mu(l)ch?

Applying mulch around the tree before it settles in for its winter’s nap is a very good idea. A mulch ring around your tree holds moisture in and protects against temperature extremes. It also decomposes and adds nutrients to the soil, too. We recommend learning the right way to mulch before getting started.

Fall Color 101

While the name Colorado technically means “colored red,” Denver’s variable fall weather makes it tough for that to ring true in our urban canopy. Sure, we have trees that could turn red in fall, but they don’t! The reason why? Red fall color relies on certain environmental conditions, such as a gradual change in temperature…and we all know those early snows in fall feel far from gradual. Plus, many of our favorite and recommended species tend towards yellow or brown fall colors, as these trees can handle the rapid temperature and weather changes we experience.

Tips for trees in cooler months:

Successful fall planting is a critical combination of good timing, a healthy tree and a simple care plan. Following these three tips, your trees will take root in no time.

  1. Good Timing – The best time to plant your fall tree is generally through October, but at minimum when nighttime temperatures are consistently above freezing. Planting a dormant tree can ensure that all the tree’s energy goes to establishing, so your tree will be well-rooted by spring.
  2. The Right Tree – From the Kentucky Coffee Tree to the Turkish Filbert, there are many trees that thrive in Denver’s climate, each lending its own beauty to our important urban forest. Tree diversity is the healthiest way to combat future pests and disease in our urban forest.
  3. Quality Care – Trees are dormant in the winter, but they still need you to keep them watered because the roots continue to grow even with what you see above ground appears to be taking its long winter’s nap. Contrary to what we’ve been told, snowmelt isn’t enough. Trees need care and watering year-round, especially in Denver’s arid climate. Just how much water is determined by the tree’s diameter. The formula is simple: 10 gallons of water for every inch of diameter of tree, with the frequency changing seasonally. (So for a 2-inch diameter tree, you need to water with 20 gallons 1-2 times a month in the winter, and more often during periods of drought (yes, we can get droughts in the winter!) Also, don’t forget to mulch, and watch for sun scald, too!

So, if you plan to plant new trees, you can use the fall season to get them going. It’s easier than you think! But if you need additional help getting going, here are some resources to find a tree care professional in Colorado.

As always, if you need more information, please contact Denver’s Office of the City Forester at or 720-913-0651.

Dutch Elm Disease: What Denver Residents Need to Know

Dutch elm disease is a fungal disease vectored in part by the elm bark beetle or spread through overlapping roots among elm trees. The disease is known to be lethal to elm trees, and it can rapidly infect neighboring trees of the same species. This disease was first discovered in the U.S. nearly a century ago – brought to the U.S. in European wood that was imported for fine furniture-making. It continues to threaten our elm trees today. Dutch elm disease is essentially incurable, so the best course of action is a hefty combination of diligence and prevention.

A term that may be new to readers is vector which comes from the Latin, vehere – which means “to carry.” Think about it like this: a vector is a bug that carries disease to people and animals. For example, consider how mosquitos and ticks spread diseases that can harm humans and pets. A beetle vector is a beetle that transmits disease, but to plants and trees. Elm bark beetles are referred to as beetle vectors of elm trees. They feast under the elm tree bark, which then spreads fungus into the tree’s “veins,” making the tree very sick and rapid decline soon follows.

These infections are worse when they take root in early spring, when the wood is still moist. But it’s still destructive in the summer. Either way, without early preventative mitigation, the tree dies.

Illustration of DEDWhen the tree becomes infected, the leaves in the high branches – or crown – begin to yellow and wilt.  Quickly, the leaves turn brown, curl up and then the entire branch dies. Branch by branch, the disease spreads until the entire tree dies. The American Phytopathological Society (APS) shares this simple-to-understand illustration on the cycle of Dutch elm disease:

Sadly, if you’ve already identified the disease, it may be too late for the tree. But there are still some steps you can take to keep the fungus from spreading.

DEDLike most tree ailments, it’s better to prevent the arrival of an illness than to cure a diseased tree. Prevention involves following good cultural practices, such as not planting too many of the same species of tree in a row, proper watering, avoiding damage to the tree, mulching, and rotational pruning. Property owners should not attempt to diagnose, prune or remove elms that may be infected, as that may unintentionally spread the disease due to beetle or fungus existing in the debris. It’s always best to have a licensed tree contractor perform tree work and remove all debris.

If Denver residents rally to prevent the spread and save the elms, we’ll see success. Below are a few photos of a local tree with Dutch elm disease at the crown. Look familiar? If you see one in a public right of way, please call 720-913-0651 or email


Urban Forest Strategic Plan

In the spring of 2023, Denver Parks and Recreation and the Office of the City Forester conducted a comprehensive community-wide survey to gather insights from residents regarding their priorities concerning trees and the urban forest across town. This valuable information is currently being utilized to craft the city’s inaugural Urban Forest Strategic Plan. The plan encompasses all trees within the city, whether on public or private property, and aims to enhance existing goals, introduce new ones, and establish a shared and fair vision for the future of the urban forest.

Trees provide numerous benefits, such as purifying the air we breathe, mitigating the heat island effect, and reducing noise pollution. They offer a welcoming environment for outdoor activities, contributing to better physical and mental well-being for residents. Moreover, a thriving urban forest enhances property values, fosters a sense of community pride, and attracts visitors, boosting the local economy. By caring for and investing in our urban forest, residents can actively contribute to a greener, healthier, and more sustainable city for generations to come.

Building on the knowledge gained from the spring survey, we now have a few additional crucial questions to ask. Your input will continue to play a vital role in shaping the plan, and we highly value your participation. Complete survey #2 by September 4, 2023.

The City Forester is Counting on You!

Hackberry Tree

Trees are a critical component in the resiliency and health of a city, and also for those who call that city “home.” Whether it’s lending charm to a shady street, shielding people and plants in the parks from the summer sun, or even stepping up to fight climate change, we really do count on Denver’s trees.

But did you know we also count them? There are more than 338,000 trees being tracked in the Treekeeper inventory kept by the Office of the City Forester today. This is a huge undertaking, and partly why we count on residents like you to help keep Denver’s trees growing strong.

From looking out for destructive pests, to learning to identify disease, to assessing and reporting structural damage, there are a few simple steps you can take to keep any tree problems from – ahem – branching out and taking root.

“The earlier we hear about a tree in need, the better. This is why having residents keep an eye out is so important. We couldn’t do this without dedicated residents who care about the urban canopy,” said Mike Swanson, Denver’s City Forester.

What the Pros Know

When Denver’s urban foresters are out surveying the city’s trees, we take a few first steps to assess overall conditions. We’re sharing some of these steps with you. A simple first-pass visual survey might include your asking questions such as:

– Does the tree look like you think it should?

– Does the tree show signs/symptoms of pests? Look out for holes in the trunk, branches, or leaves, defoliation, or oozing.

– Are there structural defects or damage? Look out for broken branches, trunk wounds, or branches lacking leaves

– Is there enough mulch?

– Is there yellowing/browning or even curling leaves in young trees?

– Is there progressive browning at the tips of branches downward, known as dieback?

If you still have concerns, you can dig a little deeper:

– Check the branch for flexibility, the hallmark of a healthy tree.

– Do a scratch test by taking your thumbnail to a young branch to see if it reveals green beneath – if it does, that tree is still living.

– Look out for common bacterial diseases, such as fire blight in fruit trees, which may present as dead branches, water-soaked blossoms and dried-up fruits.

When to Seek Help

With newly planted trees, it’s important to keep an eye on any changes that seem out of the norm. During the growing season, it’s easy to tell because leaves won’t be doing well. You may see abnormal growth such as larger or smaller than normal leaves, yellowing or browning, curling, or even no leaves. To help determine if your free tree needs attention, the quickest way to get help is to email us at

For larger trees, it may need to be brought to the attention of city forestry inspectors, especially when it’s obstructing important things like street signage or stoplights. Do you see hanging broken branches? Report the tree to 3-1-1 and issue will be routed to an inspector.

Trees are resilient. They can physically compartmentalize a lot of their bumps and bruises and heal many of their own wounds. But some issues can be difficult to bounce back from. This is why your best bet is to prevent damage before an incident harms the tree beyond repair. Most importantly, call a licensed tree-care professional if you need help, to increase the chances of a good outcome.

By keeping a watchful eye on Denver’s tree health, you’re taking care of an urban canopy that takes care of us. Together, we can preserve the beauty and benefits of trees…they’re counting on us!

Spring Cleaning – Outside Edition

Spring cleaning. Some of us look forward to this annual ritual. Others, not so much. However you choose to look at it, this annual tidying up – and wiping down – of our homes is not only good for our physical health, it’s also a good way to take care of our mental health. Plus, a good cleaning makes a space ready for whatever comes its way.

As we begin to open those windows (finally!), clean out those closets, dust the crevices and donate unwanted things we’ve accumulated over the winter months, don’t forget – your yard needs love too.

A checklist for spring cleaning the inside of our homes can be as easy as a Pinterest search. It’s not as easy, however, to find a simple list of ways to tidy up the outside spaces this time of year.

But good news! The outside is actually much simpler – and comes with a much shorter checklist. All you really need to do is follow a few key steps below to get your garden ready to welcome you in the seasons ahead.

The six steps to preparing your yard for spring include:  

  1. Aerate
  2. Turn on the irrigation system (calling in the pros, if needed)
  3. Compost/top dress
  4. Wake and rake, baby!
  5. Fertilizing (if needed) and pruning
  6. Add water!


  • Deep tine aeration may be a good option for yards that have more clay because it opens up pore space for air and water penetration.
  • Top dress with clean topsoil or organic mix to help break up the clay.
  • Make sure to mark your irrigation heads and lines and avoid visible tree roots.
  • Use limited aeration within a tree’s dripline or use a radial pattern out from the trunk, staying 1’ for every 1” diameter out from the trunk.

Schedule irrigation turn-on.

Your irrigation system has been in hibernation. It’s been waiting to emerge and bring signs of life back to what’s sat dormant all season. To conserve water and ensure your plantings receive the best treatment, it’s a good idea to call in the pros. A little investment now can save time, money and resources later on.

Compost/top dress

Spring is also a great time to show your plants some love through composting. Compost adds nutrients and organic material into the soil, something that our high elevation climate quickly breaks down. Organic material also helps break up clay and lightens soil for new roots to push through.

  • Top dress woody plants and perennials by spreading up to an inch of compost on top of the soil and gently scratching it in with a rake or hand tool.
  • Top dress once all snow is gone, leaves are budding or just opened, and new growth is just emerging for perennials.
  • Compost is also great for vegetable gardens and can be more fully dug in.
    Look for an organic product to avoid build-up of chemicals.
  • On perennial beds, compost can be used instead of mulch making it much easier to spread.
  • Compost may not be needed every year. The only way to know for sure is to get your soil tested. The test will include a recommendation for additional organic material if needed.

For more information about soil amendments; visit  

Wake & rake!

Even if you participated in our fall composting campaign, there’s a good chance your neighbors’ leaves made their way into your yard over the winter. Regardless of how they got there, it’s time to say goodbye. A good raking of what remains can clear the way for perennials to pop through when the time is just right. Raking leaves provides some additional benefits other than a “clean look:”

  • Raking action will help break down pieces incorporating into the much-needed organic matter for soil health.
  • Removes possible (re)contamination of new emerging leaves.
  • Provides better airflow to the base of plants and the soil.
  • Allows turf areas to dry out, preventing some diseases from developing. If possible, wait for the native bee emergence before removing leaves, dead plant stalks/branches or adding mulch.

Fertilizing and Pruning

  • Don’t just add fertilizer, every lawn is slightly different.
    • Get a soil test so you are only adding what is needed for best vegetation growth and not wasting hard-earned dollars or adding chemicals that will go unused and leach into the environment.
  • Check that your tools are ready, in safe working order and clean and sharp.
  • This is your last opportunity for branch pruning on elms and fruit trees. Do it before bud break to prevent spreading disease.
  • When pruning fruit trees that may have disease, make sure to clean pruning tools the right way: Wipe the cutting surface thoroughly between each cut with disinfectant or rubbing alcohol. Wearing gloves is a good idea to avoid cutting yourself.
  • Check clearance and prune branches over street/alley (13.5’) and sidewalks (6.5’).
  • Before shearing or pruning evergreens, look for bird nesting activity so you don’t scare birds away.
  • Avoid pruning thin bark trees such as maples, as sap oozing, sometimes referred to as “bleeding,” can stain bark or look unsightly. If your tree is exhibiting signs of oozing, contact an arborist as it could be a sign of insect or disease activity.


  • Outdoor watering rules are in effect May 1 to Oct. 1. Please remember to:
    • Water during cooler times of the day — lawn watering is NOT allowed between 10 a.m. and 6 p.m.
    • Water no more than three days per week.
    • Do not allow water to pool in gutters, streets and alleys.
    • Do not waste water by letting it spray on concrete and asphalt.
    • Repair leaking sprinkler systems within 10 days.
    • Do not irrigate while it is raining or during high winds.
    • Use a hose nozzle with a shut-off valve when washing your car.
    • Learn about Denver’s rules for watering. 

What’s next in 2023?

This year, we will continue to plant more trees and provide resources to residents on how we can all take care of our urban canopy.

We also want to help you plant a tree! If you have room in the public right-of-way adjacent to your property, you may be eligible to have a free tree planted for you by Denver’s office of the City Forester. It’s easy to apply online.

Let’s keep working together in 2023 to protect our urban canopy and improve the climate for generations to come. For more information about any of these programs, email or call Denver’s Office of the City Forester at 720-913-0651.

Ditch the Rocks: How One Homeowner Created a Thriving Environment for Her Tree

Jan loves trees. She always has. But she didn’t really dig in and learn to care for them herself until she moved into her Athmar Park home. The home was great, but the mostly un-landscaped double lot did not give off the homey feel of her childhood, where she had been surrounded by trees. That’s when her love for trees began to take root in a new direction. 

 “I had heard about The Park People’s Community Forester program and even signed up for the classes so I could figure out what trees would be best to plant in our barren space,” reminisced Jan. 

Her effort to reforest the front yard became even more exciting when she learned about the free trees offered by Denver’s Office of the City Forester.  

“The process of applying is simple,” she said. In 2017, Jan received her first free tree. It didn’t last. She called for a replacement. After a strong start, the second tree sadly did not survive. After these two unexpected losses in the same location, Jan reached out to Denver’s Office of the City Forester for extra help. Because of her experience as a Community Forester, Jan initially worried there might be pathogens in the soil, or some disease process that was killing the trees.

The Forestry team immediately identified the problem as not enough water – but not for lack of trying.  

“I was surprised because I had watered the tree faithfully for the first several months,” said Jan. Instead, it was the rocks around the tree that were overheating it, causing it to lose water fast.  

The Forestry team advised a quick, easy fix:  

  • Pull back the gravel away from the tree   
  • Mulch the tree appropriately (no mulch “volcanoes” necessary)
  • Use a tree watering bag that zips around the trunk  

Upon receiving her current tree, which is now thriving in its new environment, Jan says, “I have pledged to care for it and provide it a good life!”  

Landscape Materials Make the Difference  

Jan’s story proves an important point: when it comes to environmental and canopy considerations, there are better options than others when it comes to surface treatments, or materials you use to landscape. 

Here are a few reminders on what’s best and worst when it comes to creating an environment for thriving trees and plants at your home:  


  1. Organic mulch (woodchips, bark, straw, grass clippings, seed hulls) directly on top of the soil 
    • Improves water penetration and air movement 
    • Reduces surface evaporation and conserves soil moisture 
    • Great at controlling weeds, very attractive, breaks down gradually 
  2. Low water turf 
    • Healthy lawns benefit the environment! There are low water options that replace traditional bluegrass and provide a walkable alternative such as a Blue Grama, Buffalograss or Dog Tuff Grass.  
    • Lawn grass helps clean the air, trap carbon dioxide, reduce erosion from stormwater, runoff, improve soil and reduce temperatures 
    • Keep the turf away from the tree base to prevent trimming or mower damage 
  3. Alternatives to landscape fabric (beneath mulch) 
    • Healthy plant coverage is the best 
    • Consider incorporating plants like Creeping Sand Cherry, ornamental grasses, Gro-low Fragrant Sumac and Ice Plant.  


  1. Rock, stone, gravel, concrete and asphalt 
    • Create inhospitable conditions for plants and trees 
    • Retain heat and contribute to heat island effect 
    • Transfer heat to buildings and utilities  
    • Makes you ineligible to receive a free tree from the City of Denver in the future! 
  2. Artificial turf 
    • Doesn’t provide the cooling effect of a living lawn and can get very hot on sunny days 
    • Does not allow water to infiltrate underlying soil 
    • Makes you ineligible to receive a free tree from the City of Denver in the future! 
  3. Landscape fabric or plastic  
    • Prevents water from getting to plant roots and detrimental to plant health  
    • Restricts air and water movement 
    • Not needed beneath correctly applied mulch 
    • Can actually encourage weed growth after time! 

Questions about receiving a free tree? Read more about our program. Questions about why your tree isn’t thriving in its current environment? Check out our tree care FAQs