Planting a Street Tree

So, you want to plant a tree.

People want to plant trees for various reasons. Some want shade and beauty. Others want to increase the value of their property. Still others wish to memorialize a loved one with a lasting, growing tribute. Whatever the reason, if you would like to see a tree planted on public property, it requires contact with the City of Pittsburgh Forestry Division.

I want the City to plant a tree.

If you would like for us to plant a tree at a future date, please fill out the Tree Planting Request Form.

This form will register your interest in receiving a tree adjacent to your property. It also registers your intent to water the tree during establishment, and provide maintenance to the tree bed. The City will provide a site analysis to make sure a tree fits your location, and will select an appropriate species.

The City has not planted trees en masse for several years now, due to budget constraints. However, with state funding becoming available through TreeVitalize, it appears that trees are on the way.

I want to plant my own tree.

You will need a permit for planting, so fill out the Request for Permit Tree Planting, Removal and Pruning Form. The City will provide a site analysis to make sure a tree fits your location, and we will provide guidance concerning acceptability of species. Check the Planting Site Analysis checklist and diagram to see what standards need to be met when locating a tree adjacent to your property. As with City-planted trees, you also agree to water the tree during establishment, and maintain the planting bed.

When you bear the cost of planting a tree on city Right Of Way, the ownership of the tree defaults to the City. When the tree gets larger, the City will be responsible for pruning. If you plant a tree on your own, ALWAYS call Pennsylvania One Call  to arrange for a location of underground utilities or obstructions.

Their number is 800-242-1776, or you may simply dial 811.

Why do I need a permit?

City Right of Way (ROW) extends to the inner edge of the sidewalk, and sometimes well inside that sidewalk in cases where ROW is wider. You will need the expertise of the Forestry Division staff to determine what area falls under City jurisdiction. All work on City property, including planting trees, requires a permit. We seek to avoid creation of vehicular or pedestrian hazards, and ensure that utilities are taken into consideration.

The tree planting, removal and pruning form is a no-cost permit.

Citizen's Responsibility for Maintenance

No matter whether the City plants a tree, or you do it on your own at your own expense, the adjacent property owner is responsible for watering through the 2-5 year establishment period. After that, you will only need to water during times of drought. You will need to keep the tree planting area weed-free for the life of the tree.

You are also responsible for annual mulching. This will help to control weed growth, and will keep moisture in the root zone. Additionally, when you mulch the root zone instead of installing turf, there is no need to mow grass in an area where damaging the delicate trunk bark of a young tree.

How do I know what species to plant?

Forestry Division maintains an up-to-date Recommended Species List  to provide guidance concerning species. Trees planted in city Right of Way require careful forethought with regard to species in order to avoid future conflicts utilities, vehicular traffic, pedestrians, and structures.

For instance, only trees with a mature height of 25 feet or less may be planted under power lines. Conversely, where no impediments to growth are present, we like to plant shade trees in order to maximize every reason for planting trees.

Tree Quality

There are many elements to consider when selecting a tree for your site. These include cold hardiness, heat tolerance, growth rate, size at maturity, shape, pest resistance, and maintenance requirements. Check out the Tree Quality requirements for Pittsburgh, and you will see that we want a single, straight trunk with a well-formed branching structure. Most trees sold locally are balled and burlapped (B&B), but if yours was grown in a container, make sure it is not excessively root bound.

Root Zone Requirements

Roots need enough space to enjoy the full benefit of ample oxygen and water supplies. See Street Tree Root Zone Requirements 

3’ X 3’ squares for trees simply don’t provide enough space for roots to develop

Often when you see a small 3’X3’ square with a tree in it on City streets, it is a tree that is not thriving and will not have a productive life of environmental service. The City of Pittsburgh now requires a minimum standard root zone measure 3’ X 10’. This effectively triples the former square footage of useable root space, and will serve to ensure health and longevity for your tree.

Mt. Washington CDC installed prototype 3’X10’ root zones in 2006 as a test of our new standards

The prototype 3’X10’ root zone after installation of new trees on Sycamore St. at Shiloh, in Mt. Washington

Where a planting strip now exists, but is less than 3’ wide, you will be required to expand the space to the minimum width. When only concrete fills the entire space where you want to plant a tree, you will need to cut the space out of the concrete. You will want to contact Pennsylvania One Call prior to cutting or digging so you are aware of the location of utilities. Call 800-242-1776 or simply call 811 before you cut or dig.

Planting a Tree

B&B trees often come with a wire basket which maintains the integrity of the root ball during shipping. After gently placing, sliding or rolling a root ball into the planting hole, and adding enough soil to stabilize the tree before final backfilling, cut away as much of the basket as possible to assure free passage of roots as the tree grows. The planting hole itself should be 2-3 times the width of the root ball at the soil surface, but never deeper than the root ball (see Tree Planting Detail 1). One of the most common problems with planting is setting the tree too deeply.

This tree was 8” too deep in the root ball, and had to be planted higher plus the excess soil had to be removed.

Compounding the issue is the fact that often the tree arrives on site too deep in its root ball. It is important that the depth of the top main order root(s) be established before digging the hole in the first place. Untie the burlap noose at the top of the root ball, pull it back 6-12” and gently scrape soil away from the top to reveal the trunk/root flare (that area where the descending trunk flares sideways to become main roots).

Peel back rope, wire basket and burlap and cut it off

Ideally, the root flare will be visible at the finished planting depth. A tree planted too deeply may suffocate from lack of air space, or it may have air pores filled with water because the roots are too deep in the soak zone.

Heavy B&B trees often require mechanical means to lift the weight. More than one muscular person may roll or slide the root ball into the planting hole

Only a bare root tree should be lifted by the stem/trunk. A B&B or container-grown tree has too much soil weight, and if lifted by the stem it may strip the bark and kill the tree. Likewise, do not scuff or scrape the trunk during the planting process. If practical, orient the tree in the hole the same way it was in the nursery. If you can notice a dark side, possibly with a little black mold or lichen on the bark, this was likely the north face of the tree in the nursery. If you can orient the tree in the same direction, thin-barked species are less susceptible to sunscald. The West and South faces of the tree are already accustomed to receiving more direct sunlight and warmth. We know you already know the benefits of trees, and that’s why you are choosing to plant more. Don’t forget… if you are planting on public property, you need to be in touch for a permit. Good luck with your project!