Tree experts and utility companies suggest that people plant trees with a mature height of 25 feet or less near power lines, with taller trees kept farther away. Though taller trees are sometimes acceptable near power lines, they usually need drastic pruning to keep lines clear, which can be expensive and unsightly. See the picture below for guidelines on mature tree height and spacing away from overhead power lines.
There are a wide variety of small tree species and cultivars that can be planted near power lines and other places where a small tree may be needed. For example, paperbark maples only grow about 20 feet tall, are very attractive, and will not interfere with most power lines. Some tree species naturally grow 25 feet tall or less, while others have certain cultivars (cultivated varieties) that grow shorter. For example, blue spruce is a species that normally has a mature height of 60 feet or more, while the cultivar ‘Bakeri’ matures around 20 feet tall. There are many dwarf conifer cultivars that grow less than 25 feet and have the same form and color of the taller species. Some trees have weeping forms that are shorter than the species. For example, the fruitless white mulberry has a mature height of 35 feet or more while the ‘Chaparral’ weeping mulberry cultivar matures at only 15 feet tall. The double pink weeping cherry is a popular tree that only gets 12 to 15 feet tall.
Cold and heat tolerance are also very important when selecting a tree. USDA plant hardiness zones have been developed based on the average annual minimum temperatures but can give some indication of heat tolerance as well. Go to http://usna.usda.gov/Hardzone/hzm-sw1.html for a map.
Suggested tree spacing near power lines based on tree height