Q&A: Narrow Privacy Screens
Q: Which trees or bushes would provide a privacy screen in a narrow area?
A: You've asked a good question. A common challenge in many side and backyards is to provide screening in a place where typical privacy plants like Leyland cypress, photinia and various hollies have a little too much girth. Some shrubs like the juniper 'Sky Rocket' and the holly 'Sky Pencil' (a cultivar of Ilex crenata) are indeed skinny. They make great exclamation points for the landscape, and they are narrow enough to fit into a tight corner. But remember that, for a shrub, being skinny is a sword that cuts two ways — what fits into a narrow space also gives you very little coverage from side to side. Depending on how wide an area you want to provide privacy for, you could be planting literally dozens of these shrubs.
You didn't mention how narrow the space is — some plants like Leyland cypress and juniper take very well to shearing so you could go that route. But if you're talking only about two or three feet, shearing would tax the plant and be a job to boot.
One good option would be to mount a trellis on 4x4 posts and plant a climbing vine beneath it. There are lots of great choices for you to consider, including sweetautumn clematis, Caroline jessamine, or the annual vines moonvine and lablab.
Another option would be to pick a shrub that you can limb up. Several hollies such as 'Nellie R. Stevens' comes to mind.