Question
I am looking to plant Towering Poplar trees (Populus x Canescens "tower") along the driveway. I understand that this tree has an extensive root system, but not sure how extensive. What is the diameter of the root system? I want to start a shelter belt of towering poplar's that run parallel with the driveway, How far from the driveway should i plant these trees? What is a safe distance?  Thanks

Answer
The spread of the branches is about 5-10 feet meaning the branches will extend about 5-6 feet from the trunk. The roots system is about 1 1/2 times this width or about 10 feet max. It is used near buildings with no problems. I would keep it at least 10-12 feet from the drive so the branches will not overhang the drive hitting cars. The roots should not be a problem.