Tips on Planting and Pruning Trees


Illustration of proper planting techniques for new trees. (Credit: International Society of Arboriculture) Illustration of proper planting techniques for new trees. (Credit: International Society of Arboriculture)

Planting New Trees

Download this easy-to-follow guide courtesy of the International Society of Arboriculture.

The best times to plant trees are in the Fall and Spring, generally October through December and March through May.

The tree protection zone is the area beneath the trees drip line. The drip line is the width of a tree's canopy as measured by a circle extending perpendicularly from the outermost tips of the branches to the ground. Protection of this area during construction preserves the tree roots. Soil compaction and root cutting within the drip line damages roots and prevents the tree from obtaining nutrients, slowly starving a tree. Most trees will die within two-three years.

Visit Trees Are Good for detailed tree care information.


If a tree has been properly pruned then the branch tissue will be able to close up the pruning wound. (Credit: Peter Bedker, USDA Forest Service)
If a tree has been properly pruned then the branch tissue will be able to close up the pruning wound. (Credit: Peter Bedker, USDA Forest Service)
A proper pruning cut should be made just outside the branch collar. (Credit: Alex Shigo)
A proper pruning cut should be made just outside the branch collar. (Credit: Alex Shigo)
Topping not only exposes a tree to potential damage, but is also unattractive. (Credit: Larry Costello, University of California)
Topping not only exposes a tree to potential damage, but is also unattractive. (Credit: Larry Costello, University of California)

Pruning Mature Trees

Download this easy-to-follow guide courtesy of the International Society of Arboriculture.

Pruning is the most common tree maintenance procedure. Although forest trees grow quite well with only nature’s pruning, landscape trees require a higher level of care to maintain their structural integrity and aesthetics. Pruning must be done with an understanding of tree biology. Improper pruning can create lasting damage or even shorten the tree’s life.

Because each cut has the potential to change the growth of the tree, no branch should be removed without a reason. Common reasons for pruning are to remove dead branches, to improve form, and to reduce risk. Trees may also be pruned to increase light and air penetration to the inside of the tree’s crown or to the landscape below. In most cases, mature trees are pruned as corrective or preventive measures.

Specific types of pruning may be necessary to maintain a mature tree in a healthy, safe, and attractive condition.

  • Cleaning is the removal of dead, dying, diseased, weakly attached, and low-vigor branches from the crown of a tree.
  • Thinning is selective branch removal to improve structure and to increase light penetration and air movement through the crown. Proper thinning opens the foliage of a tree, reduces weight on heavy limbs, and helps retain the tree’s natural shape.
  • Raising removes the lower branches from a tree to provide clearance for buildings, vehicles, pedestrians, and vistas.
  • Reduction reduces the size of a tree, often for utility line clearance. Reducing a tree’s height or spread is best accomplished by pruning back the leaders and branch terminals to secondary branches that are large enough to assume the terminal roles (at least one-third the diameter of the cut stem). Compared to topping, reduction helps maintain the form and structural integrity of the tree.

Visit Trees Are Good for detailed tree care information.


City Trees Contact Numbers

General Tree Questions:
(302) 576-2582

Street Tree Concerns:
(302) 576-2582

Park Tree Concerns:
Dept. of Parks and Recreation (302) 576-3820

Private Property Tree Complaints:
Dept. of Licenses & Inspections (302) 576-3030

Trees and Power Lines:
Delmarva Power 1-800-375-7117

Tree Blocking Road During Business Hours:
Dept. of Parks and Recreation (302) 576-3820

Tree Blocking Road After Business Hours:
Wilmington Police Department (302) 656-4357