A fire on the corner of Wyville Road and Wynford Road, Frome, is thought to have been started deliberately.
Frome fire crews were called to the blaze, which destroyed 7m high conifer trees and badly damaged a telegraph pole at midnight on Tuesday last week.
The heat was so intense residents had to move their cars away from the fire and phone lines and broadband were out of order for a few of days.
A police spokesman said: "The owners of the hedge were very distressed by the incident. No one was hurt and we would like to hear from anyone who may have been in the area at the time."
Anyone with information should call police on 101.