Possible Clues:

• Line of shrubs
• Line of bushes
• Security problem on the border for the Greens
• Organic fence
• Line of trees chap would propagate round either side of estate
• Living boundary between fields
• Evade dispute, creating border
• Chap would cultivate around bottom of the natural fence
• Safeguard against clash at edge of road
• Sit on the fence with dispute that's between neighbours perhaps