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Denver Digs Trees Program Offers Low-Cost and Free Trees to Denver Residents

In addition to our own free tree program, we’re thrilled to share that our friends at The Park People are here to help Denver residents plant trees again this year with their Denver Digs Trees program. The program is offering over 1,000 new trees to Denver residents, businesses, nonprofits and schools, with nine beautiful and unique species available. Trees cost between $10 and $35, though residents may qualify for a free tree if cost is prohibitive. Anyone is welcome to apply, but the tree must be planted within Denver city and county limits.

Why you should apply for Denver Digs Trees

Here in Denver, we continue to see the impacts of climate change with record-breaking heat and long periods of drought. Trees help to mitigate climate change by cooling our neighborhoods, reducing energy use, capturing and cleaning stormwater runoff, filtering air pollutants and more. They are essential for a healthy city and community, and each tree in our city works to combat the urban heat island effect. Planting a tree is a tangible way to take action now to address the changing climate, while also cooling your home, adding value to your property, shading your street and bringing beauty to your community for generations to come.

How to apply for Denver Digs Trees

Do you have a Denver address, 10 minutes to spare and an interest in taking action to improve the quality of life in our communities and grow our urban canopy? If so, apply at The Park People’s website: or call 303-722-6262 for a paper application. The application deadline is Feb. 15, 2022, or while supplies last. Trees go fast, so make sure you apply early! Trees will be available for pick up and planting in April. The Park People offers planting and care workshops before the event and upon pick up, volunteers will work with you to ensure you love your tree and know how to properly care for it.

Contact or 303-722-6262 for questions or more information about the Denver Digs Trees program. The Denver Digs Trees program is just one way you can add a tree to your Denver property for low or no cost. For more information about three additional ways to get a free tree in Denver this year read more in our blog post.

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.

Winter Watering Guide: Caring for Newly Planted Trees During the Winter

Why is winter watering vital? 

In the fall and winter, trees drop their leaves and become dormant as they prepare for colder temperatures. However, newly planted trees experience the greatest growth in their root system during this time. Colorado often experiences dry periods during winter (two or more weeks without snow cover), which can leave roots susceptible to drying out, causing tree death or severe root damage. Not watering throughout the winter is the largest contributing factor to the mortality of newly planted trees. It is best to slowly give any newly planted trees 10-15 gallons of water before putting the hose away for the winter and to supplement with 10-15 gallons of water during dry periods and when temperatures are above 40 degrees. Do not water when temperatures are near or below freezing.   

Watering routine: 

  • Before winter: Continue to water your tree(s) until the ground freezes. Slowly (trickle over several hours) give your newly planted tree 10-15 gallons of water. Don’t forget to disconnect your hose so that it doesn’t freeze.  
  • During winter: Water your tree twice a month, with 10-15 gallons of water if the ground isn’t frozen. This is best done when the temperature is around 40 degrees and at mid-day to allow water to soak in before the ground freezes at night. Continue to check the moisture level of the root ball (the main mass of roots directly beneath the trunk), especially during long periods without snow cover.  

  • Following spring and summer: Continue to water the trees(s) once a week with 10-15 gallons of water and more when the weather is dry, windy or we have prolonged periods of drought and sunshine.   

Additional tree care tips for the winter: 

  • Mulch the base: Apply 2 to 4 inches of wood chips, bark or other organic mulch near the base of the tree, but not against it, to reduce soil evaporation, improve water absorption and insulate against temperature extremes. Some community recycling programs like Denver Recycles provide wood chips free of charge.  

Proper tree care during the winter months is crucial for tree health and survival. Following these watering and tree care tips can help your trees continue to grow and thrive. For additional information, read more from the Colorado State Forest Service on winter tree watering.

Three Easy Steps to Composting Your Leaves This Fall

Autumn is nearly upon us and soon your trees’ leaves will be falling. It’s the perfect time to plan ahead for what you can do with those leaves that’s easy and free for residents, and best for our city and our planet.

1. Before raking up your leaves, use this coupon to pick up a pack of free compostable paper bags specifically for leaf collection. Free 5-packs of paper leaf bags are available at participating Denver-area Ace Hardware stores.

2. While you are raking up your leaves, keep an eye out for ash leaves — they are brightly-colored leaves. Use these tips to confirm whether they’re ash.

Why focus on ash leaves? Unfortunately, the threat of losing Denver’s ash trees – which make up one in six of Denver’s trees – is inching ever-nearer with the Emerald Ash Borer (EAB) recently spreading to our neighbors in Arvada, Westminster, Broomfield and Larimer County. To prevent EAB from devastating Denver’s ash tree population, we need your help to keep an eye out for signs of EAB infestation and take action to protect your ash trees and our Denver urban canopy.

3. Keep your raked leaves out of the landfill and compost them for free through Denver’s LeafDrop program. Weekday sites will open to Denver residents Oct. 4. Weekend drop-off sites will open Oct. 30. Remember, when dropping off your raked leaves, use paper bags – they can also be composted!

Tips for Watering Trees in Denver

In Denver’s semi-arid climate, trees and water are both precious resources. However, with a few expert tips, you can preserve mature trees on your property and establish new trees that will help grow our urban canopy, diminish heat islands and combat the arrival of Emerald Ash Borer

Does my tree need more water? 

In most cases, sprinkler irrigation and natural moisture from the occasional rainstorm do not provide consistent moisture for trees in Denver. It can be difficult, however, to tell whether a tree needs additional water simply by looking at it, so follow these tips to determine your tree’s needs: 

Stick your finger into the soil at the base of your tree:

  • If it easily penetrates, the tree is adequately watered 
  • If it’s difficult to penetrate the dirt, the tree needs more water 
  • If you observe standing water in the hole when you pull your finger out, the tree is over-watered, which can be as damaging as under-watering 

 A soil moisture meter is another option for determining a tree’s watering needs.

How much water does my tree need? 

Once you’ve determined that your tree needs more water, there are some standard guidelines for determining exactly how much. Regardless of the tree’s age, a tree in a non-irrigated area needs 10 gallons of water per week per inch of trunk diameter. For example, a two-inch diameter tree requires 20 gallons of water per week. This can be spaced out over two to three days per week. 

An easy way to match your watering technique to your tree’s needs is to put a hose on a low-pressure setting and put it into a 5-gallon bucket (commonly found at home improvement stores), then time how long it takes to fill the bucket. Once you know the timing for your watering system, start a clock and move your hose around the base of your tree. 

How do I effectively water my tree? 

A simple hose is the most basic tool needed to water your tree, but soaker hoses, soft spray nozzles and soil needles can help break through the soil surface. Most absorbing tree roots are found in the first 12-inches of soil depth, so be sure water is applied slowly and has time to absorb into the soil and reach these vital roots.  

Adding mulch around the base of your tree is a simple and effective way to help retain moisture. A maximum mulch depth of three- to five-inches is optimal, but be careful not to let the mulch directly contact the trunk of the tree. 

Additional resources 

Before you begin any watering program, it’s important to get familiar with Denver Water’s summer outdoor watering rules, which take into account our high summer temperatures and recent drought conditions. And while hand-watering trees is not restricted, we encourage following the recommended watering times of between 6 p.m. and 10 a.m. to optimize your efforts.

The Colorado State University (CSU) Extension is also a great resource for tree care and other home landscaping needs, including seasonal watering recommendations that are customized to our unique Colorado climate.

Local foresters use trees to combat extreme heat in Denver’s historically underserved neighborhoods (Rocky Mountain PBS)

Denver City Forester Mike Swanson recently spoke with Rocky Mountain PBS on how the lack of trees in certain areas of Denver has resulted in the creation of heat islands. Heat islands are urbanized areas that experience higher temperatures than outlying areas.

How does Denver’s Office of the City Forester plan to combat the heat? By planting trees, of course. 

Learn more here.

Signs of Emerald Ash Borer (EAB)

One in six trees in Denver are ash trees and, if we do nothing, it’s just a matter of time before they’ll ALL be devoured by the emerald ash borer (EAB). 

EAB feasts only on ash trees (Genus Fraxinus), including the green and white varieties which are most common in the City and County of Denver.

How to identify an ash tree:

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 mature ash trees tends to have distinct diamond patterns.

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 on an ash tree) 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. This photo is showing one ash leaf, with 7 leaflets.

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.

How to tell if an ash tree is infested with EAB:

There are several signs to be aware of. S-shaped tunnels can be seen on the trunk under the bark layer and tiny, D-shaped exit holes are often visible in the bark. Additionally, impacted trees show signs of thinning and bark shedding. Dying ash trees also attract Northern Flickers, a type of large, brown woodpecker. The tree takes time to show signs of stress and often dieback begins towards the top of the tree, so it can take 2-4 years for trees to show any signs of infestation.

What does the emerald ash borer look like:

It’s small enough to fit on a penny, so you are unlikely to get a chance to examine one individually. If you do, the adult EAB is identifiable by its dark, metallic-green color and coppery-red or purple abdomen, which can be seen under its wings.

What should you do if you have an ash tree or discover EAB? Go here for more information. 

Tres maneras de conseguir un árbol gratis en Denver

Una de las mejores maneras de combatir al barrenador esmeralda del fresno (Agrilus planipennis) y ampliar el valioso arbolado de Denver es plantar un árbol en su propiedad. Gracias a la Oficina de Silvicultura de Denver, los propietarios que viven en la ciudad tienen tres maneras de obtener un árbol gratis.

Solicite un árbol gratis

Desde el inicio de la campaña “Be a Smart Ash”, la Oficina de Silvicultura de Denver ha plantado más de 10,000 árboles gratis para los propietarios de la ciudad que tienen espacio suficiente en la extensión de vía pública que corresponde a su propiedad. Es fácil hacer la solicitud en línea. Un profesional certificado en arboricultura evaluará minuciosamente su espacio y determinará el mejor tipo de árbol para su propiedad. Si usted reúne los requisitos, le entregarán el nuevo árbol y lo plantarán. Además, le darán instrucciones específicas sobre cómo brindar los mejores cuidados inmediatos a su árbol para que crezca sano. El programa está abierto a propietarios (como empresas y comunidades de propietarios) de toda la ciudad de Denver.

Plan para los espacios vacíos

Dado que en Denver 1 de cada 6 árboles es un fresno, es indudable que cuando aparezca el barrenador esmeralda del fresno se perderán algunos ejemplares, con lo cual quedarán espacios vacíos notables en nuestro bello arbolado. Con la meta de reducir la multiplicación de estos inevitables espacios vacíos, la Oficina de Silvicultura de Denver puso en marcha el Programa de extracción y reemplazo de fresnos, para retirar y sustituir los ejemplares más pequeños y en malas condiciones que hay en la vía pública en toda la ciudad. Actualmente, el programa se está llevando a cabo en las zonas sudoeste y nordeste de Denver, pero cualquier persona que esté interesada puede presentar una solicitud en línea.

Iniciativa comunitaria por la silvicultura

En 2021, la Oficina de Silvicultura de Denver inauguró la Iniciativa comunitaria por la silvicultura, que se dedica a podar o extraer los árboles que representan un riesgo para la seguridad del público. La iniciativa también contempla la plantación de árboles en la vía pública, si lo permite el espacio. Actualmente, el programa se está llevando a cabo en determinados vecindarios del sudoeste de Denver. Los propietarios que reúnan los requisitos para obtener un árbol gratis o servicios de mantenimiento para un árbol plantado en su propiedad recibirán una carta y una postal de parte de la Oficina de Silvicultura de Denver, en la cual se detallará a qué servicio o servicios pueden acceder y cómo solicitarlos. Sin embargo, tenga en cuenta que todos los habitantes de Denver tienen derecho a la plantación de un árbol gratis. Por lo tanto, los propietarios pueden presentar una solicitud en línea si consideran que tienen espacio en la extensión de vía pública que les corresponde.

Los árboles provistos de forma gratuita por la Oficina de Silvicultura de Denver son un servicio público y se deben plantar en la vía pública, pero eso no quiere decir que no deba aprovechar la oportunidad para plantar un árbol en su patio. Le recomendamos que recurra a un profesional en cuidado de árboles para que le brinde ayuda al evaluar y cuidar sus árboles, ya sean fresnos o de otro tipo. Además, si piensa plantar un árbol en su patio, consulte esta lista de árboles investigados y aprobados por la Oficina de Silvicultura de Denver, los cuales se adaptan a nuestro singular clima.

Para obtener más información sobre cualquiera de estos programas, envíe un correo electrónico a o llame a la Oficina de Silvicultura de Denver al 720-913-0651.

Para obtener más información –

For English –

Three Ways to Get a Free Tree in Denver

Apply For a Free Tree

Since the launch of Be a Smart Ash, the Office of the City Forester has planted more than 10,000 free trees for Denver property owners who have space for a tree in their public right-of-way. Applying online is easy, and an arborist or tree professional will carefully evaluate your space, determine the best kind of tree for your property and, if you qualify, the new tree will be delivered and planted along with specific instructions for how to immediately provide the best care for your tree to ensure a healthy future. This program is open to property owners, including businesses and condominium associations, across the city of Denver.

GAP Plan

Since 1 in 6 trees in Denver is an ash, it’s certain that when EAB is discovered here there will be some tree loss, which will leave noticeable gaps in our beautiful tree canopy. In an effort to proactively combat these inevitable gaps, the Office of the City Forester launched the Ash Tree GAP Removal & Replacement Program to remove and replace smaller, poor-condition ash trees in the public right-of-way throughout the city. Currently, the program is focused on Denver’s southwest and northeast neighborhoods, although anyone interested in this program can apply online.

March 2022 Update: We are experiencing delays with GAP Program removals. Thanks for your patience.

Forestry Neighborhood Initiative

In 2021, Denver’s Office of the City Forester launched the Denver Forestry Neighborhood Initiative, which is dedicated to pruning or removing trees that pose a risk to public safety. This initiative also includes planting trees in the public right-of-way, as space allows. The program is currently focused on specific neighborhoods in southwest Denver. Property owners who qualify for a free tree or for tree maintenance at their property will receive a letter and a postcard from the Office of the City Forester outlining which service(s) they qualify for and how to claim them. However, everyone in Denver is eligible for a free tree planting, so property owners can apply online if they think they have space in their public right-of-way.

Trees provided free by the Office of the City Forester are a public amenity and must be planted in the public right-of-way, but that doesn’t mean you should ignore the opportunity to plant a tree in your yard. We strongly encourage you to enlist a tree care professional to help you evaluate and care for your trees – ash or otherwise. And, if you’re looking to add a tree to your yard, consider this list of trees researched and approved by the Office of the City Forester that do well in our unique climate.

For more information about any of these programs, email or call the Denver Office of the City Forester at 720-913-0651.

Para español –

Help the Office of the City Forester Protect and Diversify Our Urban Forest: Become a Smart Ash

By Office of the City Forester Operations Assistant Lexi Brewer


The Emerald Ash Borer (EAB) is an invasive insect first discovered in the United States near Detroit in 2002.

It’s believed that EAB likely arrived in the United States on lumber in cargo ships originating from its native Asia. It has killed hundreds of millions of ash trees in North America and has been discovered in over 35 states, including Colorado. In fact, it’s been found in surrounding metro areas including Boulder and Arvada, so it’s just a matter of time before it is discovered in Denver. All ash trees that are infested with EAB eventually die because the larvae feed under the bark of ash trees, disrupting the tree’s ability to transport water and nutrients. Because of this, the dieback of the tree is a slow process, starting at the top of the tree. Since one in six of Denver’s trees are ash, Denver’s Office of the City Forester has been proactively preparing and planning for the EAB’s inevitable arrival for more than five years through planting, tree removal and replacement, and treatment activities.

Be A Smart Ash Program

With guidance from management practices such as “Slow Ash Mortality” and experiences learned from states like Michigan that have battled EAB for nearly 15 years, the Office of the City Forester created the Be A Smart Ash program in 2016 to drive awareness and inspire the community to take action to protect the ash trees on their property. Depending on the condition of the ash tree, homeowners are encouraged to either treat their tree with insecticide or remove and replace it with a new, non-ash tree. The arborists at the Office of the City Forester are happy to assist homeowners in determining the best care for their trees.


The only way to ensure that ash trees survive EAB is to have them treated with insecticide, of which there are a variety of options. Homeowners can visit to find out more information on how to treat their private property trees. For public ash trees, the Office of the City Forester is actively taking steps to treat ash trees in public spaces and in the public right-of-way within our city. The Forestry team is now on Cycle Six of treatment, meaning many trees in public spaces or in the public right-of-way are receiving repeated treatment.

If homeowners decide to keep and maintain their ash trees, there are three main treatment methods: trunk injection, soil drench or bark spray.

Trunk Injection: A licensed pesticide applicator drills a hole in the base of the tree and injects the tree with an insecticide. The insecticide is conducted by the tree’s vascular system and ultimately into the cambium layer. Since the EAB larvae hatch and feed on the cambium layer, this stops the spread by preventing the larvae from becoming reproductive adults. When properly administered by a licensed tree care professional, some trunk injections have shown to be 90% effective at controlling EAB, making this the most effective treatment option.

Soil Drench: A licensed pesticide applicator will clear the area beneath a tree and then apply liquid or granules that are then watered-in. This allows the tree to soak up insecticide through its  root system.

Bark Spray: A licensed pesticide applicator sprays up to 18 inches from the soil up the trunk. This insecticide soaks through the bark and is transferred to the leaves of the tree. This helps to stop the spread of EAB as it targets the adults who feed on the leaves of the tree.

Removal and Replacement

Ash trees that are left untreated will eventually succumb to EAB. With this in mind, it may be more effective to remove ash trees that are already dead or dying and replace them with new, healthy trees (not another ash). In 2020, Denver’s Office of the City Forester created the Ash GAP Program to remove and replace smaller, poor-condition ash trees in the public right-of-way throughout the city, encouraging homeowners in target neighborhoods to opt-in to the program. The City is targeting small diameter ash trees in poor condition because trees that are already stressed are particularly vulnerable to EAB. It is also recommended to remove smaller ash trees and replace them with a species not susceptible to EAB, as ashes will need proactive EAB treatment throughout their entire life in order to survive an EAB infestation.

In 2021, the program is focusing on Denver’s southwest and northeast neighborhoods, although anyone interested in this program can apply at Removing unhealthy ash trees from the urban forest not only promotes a healthy forest, it removes a food source that EAB would feed on while eliminating unhealthy trees that would be targets for EAB.


Of course, planting and maintaining new trees is the best way to have a resilient, healthy forest. New plantings will help fill any gaps in the canopy after the demise of ash trees from EAB. Planting for diversity also increases the resistance of Denver’s urban forest to any potential future pests. The Office of the City Forester has always encouraged qualifying homeowners to apply for a free tree. Since the start of the BASA program along with other programs, the Forestry team has planted over 2,000 trees a year in Denver. Any Denver resident who has adequate space in their public right-of-way is encouraged to apply for a free tree at

Want to learn more? Become a Smart Ash and join us in our fight against EAB!