If you live near overhead power lines, you have probably seen crews out pruning trees that are too close to the wires. The trees end up in a V shape with a notch in the center. This isn’t healthy for the trees and isn’t aesthetically pleasing.
Tree versus Power Line
Trees are the most common culprit in downing power lines, causing blackouts for the areas around the problem. The tree can conduct electricity from these wires to the ground, electrocuting anyone who touches the tree. The electricity can also start fires and destroy structures. The Camp fire that destroyed Paradise, California in 2018 was started by a downed power line.
Electrical Lines Take Precedence
In most states, electric providers have the right to prune or remove any vegetation that interferes with the overhead lines. The distribution lines that go to houses are usually on poles 30-40 feet tall. Short trees or shrubs are generally allowed under the lines, but workers must be able to reach the poles. No brambles or other plants that might make it hard for linemen to get to the poles are allowed.
The company will also maintain electrical easements where the massive power transmission towers are. The rules for this kind of utility easement are much stricter. Utilities usually require written permission to plant anything in the easement. This generally means the easement will be kept in short plants that don’t block workers from reaching the lines. Trees are not allowed under these lines.
Acceptable Pruning Strategies
There are two pruning choices for trees around power lines. In the past, trees were simply topped. Everything above a certain height was removed. This is very bad for the tree. Water sprouts from the topped branches soon sprout and grow into the lines, defeating the purpose of topping. Topping also eliminates too many of the branches with leaves on them. The tree slowly starves to death if insects and diseases don’t get it first.
The other option is called directional pruning. Branches are pruned so the tree grows into the V shape I mentioned above. This is better than topping but can leave a tree with unbalanced branches and put undue stress on the tree. Branches may break off and damage anything under them when they fall. Directional pruning works better with trees that have spreading canopies, like maples and elm. It doesn’t work as well with upright species like oak and pine.
Tree Removal
Sometimes, the tree creates too significant a risk to the power lines for pruning to help. If the tree is old or diseased, utilities may choose to remove it. On the positive side, this saves the property owner from paying to remove a hazard. In exchange, some utilities will provide small trees that will not grow tall enough to be hazardous.
Plant Utility-Friendly Trees
The easiest solution to power line versus tree conflicts is not to plant tall trees under power lines. Do not plant any tree that grows over 25 feet within 20 feet of the power line. This height is low enough to avoid interfering with the power lines.
A tree can still cause a problem if it falls across a power line, so you should not plant anything over 40 feet tall or with any part of its canopy within 10 feet of the power lines. Trees of this medium height will not be able to fall on the power line if they get uprooted in a storm.
Tall trees have their place on properties near power lines. They should be planted at least 40 feet from a power line. You will only want a few tall trees as they dominate the landscape. Do not plant fast-growing, weak wood trees to ensure the trees do not fall onto a power line. Stick to strong, slow-growing trees.
Small trees should have an upright habitat so they do not block the sidewalk or street. Even small trees with a spreading canopy can be problematic for those two areas.
Perennials and Shrubs
Of course, you are not limited to trees when planting under a power line. Landscaping under power lines that use shrubs and perennials is allowed as long as you leave a path to the power pole. A combination of shrubs and perennials can be planted to screen the sight of the power lines out. In addition, such plantings can screen out or reduce noise from street and sidewalk users. The plants need to be far enough from the sidewalk and street so that they will not obstruct either one at their mature height and spread. Upright plants are preferred to more round plants.
Choosing Plants
Many utilities provide lists of preferred trees that grow well in the area and do not interfere with power lines, sidewalks, and streets. Some cities and counties also publish such lists. Choosing native trees and shrubs means they do not need as much care once the plants are established. Most areas have abundant native species that will work for plantings. In addition, many dwarf species of familiar trees are now available. Here are a few small trees and shrubs we carry that work well and grow well in urban areas.
Silky Dogwood
Silky dogwood trees have bright white flowers that pollinators love. The birds love the fruit, too. Silky dogwood trees grow up to about 15 feet.They grow in seasonal wetlands, floodplains, stream banks, and forested wetlands. Silky dogwoods are happy in dappled sunlight and part shade.
Pawpaw
Pawpaw trees are short with green leaves. They are deciduous and produce an edible fruit. Pawpaws were once common throughout the South, but as forests and bottomlands have been cleared, they have become rare. Young leaves and shoots are covered with a rusty colored down but become smooth as the leaves and stems mature. The blooms are white, red, yellow, or purple and appear in the spring. You need two trees to make a lot of fruit.
Elderberry
Elderberries not only look nice, but they also have berries that are sometimes used to make wine, jams, and jellies. The white flowers are in big, conspicuous clusters. The berries are blackish purple. The plant will grow in full sun but is usually found as understory along streams and wetlands. It can be aggressive about spreading, so may need to be cut to the ground every other fall to keep it in check.
