Yes, but it's best not to put a mirror. Mirrors play a very important role in geomantic omen, which requires experience and careful use. If you don't make good use of it, it is ok to put plants, but if you put them outside the door, will they be easily taken away by others? You can put a mat at the door and choose colors according to the orientation, such as southern red, northern black, eastern green and western white. Under a string of six emperors' money, pure.
It's also good to communicate with people across the hall. This problem can be solved, and there will be other benefits to putting the money of the six emperors.