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Arborists: The Unsung Tree-Care Pros Who Keep Our Trees Growing Strong and Living Long

The weather is slowly warming up, birds are more frequently chirping and the sun’s setting later—which means spring must be approaching in the coming months. This also means it’s time to start preparing for your spring gardening and tree care needs. And no one is better equipped to help get your trees ready for spring than a tree care professional, also known as an arborist.

What is an arborist?

An arborist is a specially trained tree care professional who has expertise on how to plant, care for and maintain trees. In order to perform tree work in Denver, all contractors must be licensed and insured by the city. Licensed arborists help the City of Denver and property owners maintain private and public trees through tree removal, pruning of dead, diseased or damaged branches, and treatment of insects and diseases. This maintenance helps ensure our urban forest remains heathy and resilient and prevents potential damage to our properties, city rights-of-way and utilities.

What does an arborist do?

Think of arborists like a primary care provider for your trees. They can help assess a tree’s condition, provide recommendations based upon the needs of the species and complete the necessary work, ensuring the health of the tree. Services arborists can provide include:

  • Pruning: Arborists can help you determine what kind of pruning your tree needs, including improvement of health, appearance and safety of the tree. This may include removing limbs that interfere with utilities or structures or obstruct streets or sidewalks. While some pruning can be done on your own, if you’re pruning a large branch or anything from your tree that can’t be reached from the ground, be sure to hire a tree care professional.
  • Tree removal: Some trees, like ash trees, are susceptible to an invasive insect called Emerald Ash Borer (EAB) which impacts all ash species and quickly kills untreated trees.  If you need assistance removing a right-of-way ash tree, Denver’s Office of the City Forester can potentially help through the Ash Tree GAP removal and replacement program. Thyronectria Canker is increasingly common on honeylocusts and is easily spread between trees if pruning equipment isn’t properly disinfected between cuts.
  • Emergency tree care: Removing or pruning storm-damaged trees may be necessary after severe weather events to keep trees healthy and to ensure broken or damaged limbs don’t pose a risk to you or the public’s safety.
  • Planting: Arborists can also help with getting a new tree off to a healthy start by assisting with planting and creating a care plan that you can implement with ease. If you’re interested in planting a tree in the public right-of-way adjacent to your Denver property, you can apply for a free tree.

Why should I hire an arborist?

Trees are assets on our properties. They provide natural beauty year-round, summertime shade and a place for our flying friends to rest their wings. They increase the value of our homes, provide numerous environmental benefits and improve our quality of life and mental health. They’re also an investment—meaning they require proper and regular care. When it comes to caring for your tree, arborists are specially trained and equipped to perform the necessary work.

Depending on what’s required, tree work may be dangerous for homeowners to perform themselves. Licensed arborists are insured and specially trained in safety precautions while treating trees and will come to your property prepared with the appropriate equipment and training to keep themselves, the public and your property safe while caring for your trees. Every tree is unique, and each requires a different plan of care.

What should I look for when hiring an arborist?

When looking to hire tree care professionals, you may want to make sure the company has an International Society of Arboriculture (ISA) Certified Arborist on staff. This certification ensures an individual is proficient in the competencies needed for proper tree care. ISA Certified Arborists have knowledge in areas like tree biology, diagnosis, maintenance practices, proper safety procedures and other subject and practical areas within the tree care industry.

Where can I find an arborist in Denver?

Denver’s Office of the City Forester provides a helpful list of tree care professionals in Denver.

Professional, trained arborists know how to properly maintain trees for the safety of the public and the health of the tree. The best way to ensure your tree stays healthy is to hire a professional arborist. Watch this video to learn more about arborists.

Tips and Tricks for Pruning Your Trees

By Urban Forestry Operations Assistant Paul Cancik

With spring upon us, many residents are eagerly planning their gardens and starting to spruce up their yards. Pruning helps trees live longer, which allows them to grow taller and contribute to Denver’s urban canopy. With this in mind, Denver’s Office of the City Forester is offering helpful tips for pruning. It’s important to keep in mind that if you cannot safely prune your tree from the ground, it’s best to hire a licensed tree care professional since they use specialized equipment and have the necessary field knowledge. When you prune a tree, you are planning for the future, and with patience, you will ultimately have results that benefit generations to come.

Why should you prune your trees?

  • Pruning helps ensure that your tree develops a strong form/structure and prevents breakage in the future. 
  • Thinning your tree makes the crown (top) healthier by allowing more air and sunlight to pass through it. 
  • Pruning, much like watering, helps give your tree longevity; future generations will be able to enjoy it.
  • Removing deadwood from your tree helps prevent insect infestation.
  • If pruning is neglected, a tree can become susceptible to breakage, making the tree potentially dangerous.

What should you prune from your trees? 

  • Follow the “3 D’s” of pruning: only remove Dead, Damaged and Diseased wood, especially if the tree is not established. You can also prune branches that impact the structural integrity of the tree. 
  • Be deliberate about what you prune from a tree. 
  • It’s important to prune around stop signs and to ensure sidewalks are clear to prevent accidents on or near your property. Stop signs should be clearly visible and sidewalks free of obstructions. The clearance requirements in Denver are 8’ above sidewalks and 13.5’ above streets and alleys.

When should you prune your trees?

  • While you may prune your tree year-round, ideally the best time to prune is late in the dormant season or early spring, before leaves form. This is typically a good time to remove excess or undesired branches because the tree is not putting forth energy to create foliage.
  • Certain trees, including American elm (Dutch elm disease) and fruit trees in the rose family (fire blight) should only be pruned while dormant to reduce the spread of disease.
  • Only prune a young tree two years after it has been planted and just focus on dead, broken, crossing and interfering branches.  

Tips for pruning:

  • Make sure that every pruning cut you make is clean and smooth. The best tool to use for pruning is a pair of sharp bypass hand pruners for one-inch branches because they make smaller cuts that the tree can recover from faster.
  • Colorado has a very short growing season compared to other regions. A shorter growing season means the tree has a shorter period of time to create and store energy, which ultimately affects how quickly a tree can recover from pruning. A young established tree can tolerate removal of 1/3 of its foliage in a growing season. A mature tree should never have more than 25% of its live foliage removed in one growing season. 
  • If you are pruning something off your tree that you can’t reach from the ground, it’s advised that you hire a tree care professional since they use specialized equipment such as an aerial lift truck/bucket truck and they have the needed field knowledge and expertise. In the City of Denver, tree contractors are required to be licensed and insured. A list of Denver’s licensed tree contractors can be found by visiting https://www.denvergov.org/forestry.
  • If you suspect an insect problem, contact a tree care professional to develop the most effective and environmentally conscious solution. 
  • Covering a wound or using wound dressings is not recommended and may be detrimental to tree health.

Want to learn more? Our friends at The Park People offer a community forester program with classes that cover a variety of topics, including pruning and tree planting basics. You can sign up here: https://theparkpeople.org/What-We-Do/Community-Forester-Program

 Happy pruning!