How tall, and what is the size of the planting area?

There's a tall narrow boxwood called 'Green Tower'. You will need patience to get an effective screen, because it's not a zippy-fast grower, but it would be a long term, effective solution. To about 10' tall, 2' wide. I'm very happy with mine.

If you want fast, Ligustrum or Photinia is the way to go. Just cut off the flowers.

Here is a link that might be useful: green tower buxus

trying to get to 12-14 ft height - have about 50 feet of wall - thanks

Sorry I was not more clear in my earlier post. The more important size information needed is the size of the bed out from the wall--the width of the planting area.

I have a similar challenge.. 50ft long fence line, 4 feet in width. USDA zone 10. I have had clumping bamboo in barrels but the litter is significant and it is all year. Does anyone have any experience with Dodonaea viscosa?

Dodonea looks good for a few years, then starts to die. It is a short-lived plant, which is fine (for the plant) because it reseeds with abandon. It drops quite a bit of litter. It's not all that dense in habit. If you want something for a few years, it's a quick grower with not much of a root system. I left mine about 10 years then pulled them all out and replaced with a narrow growing Pittosporum.

Narrow, tal, fastl screening plants without flower, leaf drop, or invasive roots that isn't an Italian cypress cultivar is the Holy Grail of the horticulture world.

I have a very tall podocarpus gracilior hedge around our pool on three sides which I affectionately refer to Hedgezilla. Yes, it can get big, but to keep it under control in a small, tight suburban setting as ours is, it becomes a maintenance nightmare which I've delegated to a very expensive tree-trimming company. Yes, this plant doesn't break or lift concrete or create oodles of litter, doesn't have thorns and is disease- and pest-free, and never needs water once established. (Ours has been in since the early 90s.) But, it's boring. Boring. BORING. Worst of all, it doesn't provide any wildlife benefits or visual interest. I hate it. It's the bane of my existence. I've decided to gradually replace it with a selection of plants that will be more natural looking, provide some wildlife benefits, and won't require a heavy-handed, man-made intervention on a regular basis.

Around pool equipment in a tight area, I have some upright rosemary (it doesn't pop up everywhere like some rosemaries can). It's easily trimmed to keep neat (but doesn't get huge and require a lot maintenance), isn't picky about soil, doesn't like a lot of water, has a nice scent if you brush against it, and you can use it in cooking, too! It flowers a bit (mine gets partial shade), but I don't see a lot of bees on it.

I have a similar challenge: a 40 ft long short wall (4 ft tall) & need immediate 10ft-12ft tall privacy in a 5ft wide planter area (between a retaining wall & a pool)- need an evergreen hedge or tree w low litter, non-invasive roots, no berries or blooms during the swimming season (late May-late Sept). Los Angeles area. TIA.