One of the things that make Denver such a beautiful, livable city is our diverse, magnificent array of trees. Trees provide shade in the summer, screen our homes from winter winds, paint the autumn with a variety of colors, produce oxygen, clean the air of carbon dioxide, buffer noise, and increase the value of our homes. So, naturally, growing a healthy urban forest is important to all of us.

When it comes to deciding what species to plant, and where and how to plant them, most homeowners are in the dark. That’s why the Forestry Division at the City and County of Denver has prepared this helpful guide. It shows you what species are recommended to be planted along the public right-of-way. It also provides helpful tips on properly planning, planting, and maintaining your street trees. For more information, contact the City Forester’s Office at 720-913-0651.

 

Acceptable Street Trees (PDF)

Water 

Matching your site with the right tree assures fewer problems and more years of enjoyment. Be sure to avoid planting large trees under power lines.

 

Permits (no charge) are required for planting, pruning, or removing trees in the public right-of-way and may be obtained by calling 720-913-0651. This process will also ensure the right tree is planted in the right place.

 

Not permitted in the public right-of-way are: Siberian elms, willows, Russian olive, boxelders, any poplar species, evergreens, weeping trees, trees that produce fleshy fruit, or multi-stemmed trees.

 

Spacing Requirements

35’ between shade trees
25’ between ornamental trees
30’ from curb at intersections
20’ from street lights
10’ from alleys, driveways & fire hydrants
7’ from attached sidewalks

The most common problem seen in tree planting is planting too deeply. Trees should be planted so that the top of the root ball is approximately 1-2” above the surrounding grade. This helps tree roots get the oxygen that is essential to plant growth.

Measure the height and width of the rootball (on balled and burlapped or containerized stock) and dig the hole to a depth slightly less than the height of the rootball, but twice as wide.

For bare root stock, dig a hole wide enough to spread out the roots, but just deep enough to cover the roots: generally no more than two inches of soil should be placed on top of the roots. Slowly and thoroughly water root zone after planting.

Staking is needed only if the tree is exposed to strong winds. When staking, install guying materials loosely enough for the tree to have an inch or two of sway. Trees develop strong root systems on response to their ability to sway slightly. Remove all staking material within one year after installation.

Roots are frequently the least understood part of a tree. There are two types of tree roots: anchor roots and absorbing roots. As the name implies, anchor roots are the larger, woody roots that help to support the tree. The smaller and finer absorbing roots provide the mechanism by which water and nutrients enter the tree.

Both types of roots are essential for healthy tree growth. As a tree matures, roots develop laterally, but generally to depths of ten to fifteen inches. Roots on a mature tree may have a spread of at least twice the height of the tree. Keep in mind where tree roots are growing in your yard as you consider construction projects or other activities that can impact their health.

Mulch

A good organic compost can be used at planting time so long as it is thoroughly mixed with the soil from the hole. Never layer compost or any other material when planting as this creates an ‘interface’ or a change of growing conditions. Due to more years of cultivation and organic accumulation, older parts of town have better soil conditions than more recently developed areas.

Fertilizer
It takes energy for a tree to absorb fertilizer. It is therefore recommended that fertilizer not be used at planting time, or for at least a few years after. Allow a tree to spend all of its energy after transplanting in re-establishing its root system.