Caring For Urban Trees

Urban trees face more threats than their forest counterparts. On top of disease, storms, and pests they also face pollution, compacted soils, limited space, and physical damage. The life of an urban tree can be tough, and these trees often have shorter lives as a result. Trees may also represent a potential liability if not maintained when near buildings, cars, and infrastructure. Care and maintenance are critical to preventing accidental injury or damage and increasing a tree’s life span and benefits.

Trees should be checked at least once a year, especially after storms or damage. Trees typically do not die suddenly but decline slowly over time. Checking them regularly will help identify issues so they can be addressed and reduce the risk of property damage.

Young Tree Care

Some tree species are more likely to have issues or be damaged due to their characteristics. Structural defects such as codominant stems (when two or more stems grow upwards from the same point on the main trunk), weak branches, and decay can make a tree more susceptible to storm damage. The risk of defects can be dramatically lowered by following best practices for tree planting and tree pruning—especially in young trees. Removing weak branches and correcting poor form when branches are small will minimize the size of the pruning wounds and increase the likelihood of the tree healing.

Newly Planted Trees - Support and Protection

The use of stakes for support with newly planted trees is often not necessary. Trees tend to develop stronger trunk and root system if they are not staked. Protective staking may be beneficial in places where lawn mower damage, vandalism or windy conditions are concerns. If trees are staked, there must be a plan to return and remove the stakes after one year. Leaving stakes too long will cause long term damage to the tree.

Seedlings planted in rural or natural areas usually benefit from tree tubes or other sorts of protection that deter hungry wildlife. See our Tree Planting and Maintenance Guide under Additional Resources for details.

Mulch

Mulching young trees helps maintain soil moisture, prevent weeds, and provides nutrients. Apply organic mulch  in a circle around the tree base, about a foot wide and 2-4 inches deep. Mulch should not touch the trunk or trunk flare. Mulch placed against the trunk will damage the tree - it can lead to mold, pest damage, decay, or even death. Never bury a tree’s trunk and roots in too much mulch.

Water

Water is essential for newly planted trees. Water your trees, soaking the root zone, at least once a week and more frequently during hot weather. When the soil is dry below the surface of the mulch, it is time to water. But be aware that too much water can be just as harmful as not enough. The right amount of water depends on the site conditions and tree species.

Tree watering bags are a good option as a portable drip-irrigation system that slowly releases water. This reduces the possibility of too little or too much water applied to newly planted trees.

Young Tree Pruning

Wait to prune newly planted trees until they have been established for a year or two. At planting time, limit pruning to removing dead, broken, or diseased branches. Pruning young trees should be done to encourage strong branching and prevent future issues. When pruning young trees:

• Remove any competing leaders—a tree should have one primary trunk;
• Remove any water sprouts or suckers from the ground and base of the tree;
• Remove damaged, broken, or dead branches;
• Inspect the areas where branches join the trunk, U shaped joints are strongest; remove V shaped joints;
• Don’t leave branch stubs, remove branches at the branch collar—the visible ridge and collar shape near the trunk where the branch joins it;
• Think about the shape you’d like the mature tree to be; and
• Don’t remove too many branches at once.

Mature Tree Care

Proper care and maintenance of urban trees maximizes their benefits and minimizes liability. The primary concern for maintaining trees is safety—safety of the people working on the tree and those who live near the tree. Neglected trees can become hazards. Mature trees can be damaged by severe weather events, like storms, and grow old like all living things increasing the possibility of a hazard and risk.

When caring for your tree there are several things to consider:

• Insurance:  homeowner's policies may partially cover the cost of tree removal if there is damage to structures, houses, or possessions.
• Be conservative: If a tree is damaged, address any immediate hazards and evaluate the tree. Damaged trees may still serve their intended function. Trees are strong and can heal over time. Removal is not always necessary. If you're unsure, find an arborist — they can give you an assessment and make recommendations for saving or removing the tree.
• If the tree is badly damaged and must be removed, consider replacing it to gain the same benefits! Learn more about planting trees.
• Power lines and utilities: Any branches near power lines pose a danger. Do not attempt to prune branches near or on powerlines. If there are limbs on or near powerlines, contact your local power company. They will send someone with special training to address the issue.

Pruning Trees: The Basics

Before you begin

Improper pruning can cause further damage and shorten a trees life. For best pruning practices first keep safety in mind:

• Work on branches you can reach from the ground or with a pole saw.
• Trees and branches that are too large to handle or cannot be reached from the ground should only be pruned by professional tree-care services or arborists.
• Before starting, look at the whole tree for loose branches that could fall while you are working. Wear a hard hat and safety glasses to protect yourself from falling branches.
• Branches that are cracked or broken should be removed. A branch (or trunk) that was partially stripped of its bark and lost a third or more bark around the circumference should be removed as well.

If the branch can be safely removed, you can start pruning. Proper pruning may require multiple efforts over time. Do not remove more than 20-30% of a tree’s canopy in one year. Poor pruning can leave a wound that will shorten the tree’s lifespan. The larger the branch removed, the larger the wound left behind and less likely it is the tree will fully heal.

When pruning, be careful not to injure the tree further by damaging other branches or the trunk. Choose the proper pruning method that will minimize further damage to the branch or tree, especially when pruning broken or cracked limbs.

Pruning is best done in late winter and early spring. Low humidity in winter can slow or stop healing as the cut dries out. Trees also need the energy stored in their branches during the winter. If a tree takes damage in the winter, remove the broken branches, and return in the spring to fix the broken area.

If you are pruning oak trees, avoid pruning them in spring or summer unless absolutely necessary. Oaks are susceptible to oak wilt at these times. Learn more about oak wilt and how you can help.

How to Prune a Branch

• Prune at the right spot: Find the "branch bark ridge" or "branch collar"—where the branch meets the supporting stem (see reference photos to the right ).
• Branches should be pruned using a series of three cuts  : two to remove the weight of the branch (first under then over the branch), then the final pruning cut.
• Begin the cut just outside the branch bark ridge and angle down and slightly away from the stem.
• Avoid injuring the branch collar.
  • The branch collar can heal and close over the wound.
  • Do not cut flush against the tree, this removes the branch collar and increases the risk the wound will decay.
• Branches that have pulled away from the trunk should be removed at the bottom of the split. Avoid causing any additional damage to the trunk. Remove any loose bark, but do not cut into bark that is living and still attached.
• Dispose of branches correctly.
• Do not cover or seal the new wound from the branch removal, this may interfere with wound healing.

Assessing Trees for Risk

Proper tree care and maintenance are the best ways to reduce the risk of damage or harm from trees. To further reduce risk, especially around mature and declining trees you can:
•    Remove property from under or near trees, especially if any defects are present in limbs;
•    Visually inspect the tree for defects; — the more defects present, the greater the potential risk of failure and more likely it needs a professional inspection;
•    Do not try to save, brace, or support a tree in any way without guidance from a professional tree care expert; and
•    When in doubt, contact a certified arborist for a tree risk assessment.
Checking in on your trees regularly will help you become familiar with them and notice changes in their health over time. If something changes, especially after a storm, it may be a sign a professional inspection is needed.

Defects in trees

How to Find a Tree Care Professional

Hiring professionals to assess and care for your trees requires careful consideration. Qualified professionals will perform the work safely and properly to ensure the continued health of your tree. Unqualified people may cause further damage and burden clients with potential liability. Tree care work is hazardous and requires training to perform safely.

Arborists are qualified professionals, certified by the International Arboriculture Society (ISA). ISA Certified arborists receive specialized training and pass a test to become certified and then must maintain their certification through ongoing training and education. You can learn more about ISA certification and find ISA Arborists near you by visiting the ISA website.

Many professionals in the tree care industry may not be certified arborists, but they may be members of the Tree Care Industry Association (TCIA). TCIA offers training, support, and resources to its members. Learn more about TCIA and find TCIA member companies.

Selecting a tree care company can be a challenging task. For the safety of yourself, your family, your property, your neighbors, and your community, it's important to work with qualified professionals. Here are some points to keep in mind when hiring or contracting with an arborist or tree care service:

• Check online on contractor listing sites or with a web search for tree care services near you.
• Be cautious of professionals or companies that advertise "topping" as a service - topping is a poor practice, injures trees, and creates weak branches more prone to failure.
• Ask for certificates of insurance, including proof of liability for person and property damage and workman's compensation. Then contact the insurance company to make sure the policy is current. Under some circumstances you could be held financially responsible if an uninsured worker is hurt on your property or if the worker damages a neighbor's property.
• Ask for local references or look for references online. If possible, look at the work and speak with former clients.
• Don't rush into a decision because you are promised a discount if you sign now. Be sure you understand what work is to be done and what the cost is. In general, don't pay in full until the work is completed.
• Get multiple estimates from different contractors and let them each know you are soliciting multiple bids.
• Most reputable tree care companies have all the work they can handle without going door to door. People who are not arborists may solicit tree work after storms, seeing an opportunity to earn quick money. Storm damage creates high risk situations for both workers and property.
• Legitimate professionals never ask for payment in advance.
• A conscientious professional will not use climbing spikes except when removing a tree. Climbing spikes open wounds on the tree that can lead to decay.
• Know that good tree work can be expensive. A good professional must carry several kinds of insurance as well as pay for expensive and specialized equipment. Removing urban trees in close proximity to people and property may require highly specialized equipment and be done slowly. Beware of estimates that fall well below the average because there may be hidden costs or the professional may not be fully insured or trained.