Nice to hear from you again!

The light is bad in the pictures. I can't tell the limits of where you are looking to add more plants. Since we are looking at creating background, it might work best if the camera is located near a central position of the yard and you show contiguous perimeter in slightly overlapping shots. I see one bushy thing and others that look like small evergreen trees. What are these things?

That viburnum will be in the pool in a few more years They easily get 12 feet wide, maybe more. Wider than tall.

The viburnum is approximately 10' from the pool and hasn't actually spread that much in 5 years. I'll prune when it gets bigger and if it gets too big I'll replace it.

I measured and there is 10' from the fence to the pool and approximately 12' from the junipers to the viburnum. Here are some more (and hopefully better) pictures:

From deck off the back of the house looking toward the back of the lot. The yellow circle indicated where we'd like to add a screen.

View from the pool deck looking back

Back of lot line

Back of lot line again

Why not just extend the 'Skyrocket' Juniper since it seems to like the environment and will do the job of creating a screen without occupying too much ground space?

Thanks Yardvaark. I already have 10 planted (in an L along the back right corner of the yard....some you can see in the pictures) so was thinking something different. I remember your a strong advocate of planting the same trees/shrubs/plants in groups but in this instance do you think this will be too many of the same tree?

And I still adhere to the notion that a more common problem in landscaping is too much variety as opposed to too much sameness. Of course, it's subjective and everyone makes their own call. Here, you're creating a backdrop of sorts to the pool area. Yet it seems to stop about even with the center of the pool. It seems to me it would look better if it spanned the entire, or most of the entire background area of the pool, especially because that's where the pool is closest to the property line and where you need the screen to be the thinnest. Once you pass the pool, you can use fatter plants. In compliance with the theory that underlies this principle, you could use a different thin plant to complete the perimeter screen. But that seems to me akin to changing materials, textures or colors for the last 15% of a house wall.

Sounds good. Any idea how many feet I should plant the first juniper from the viburnum? Should I be concerned with buying from the same seller? Do colors vary from one nursery/seller to the next?

Doesn't matter the seller so long as actual 'Skyrocket'. Will be same plant when named (unless there is a mistake!) Keep same spacing starting from existing plants. Leave a 5' or 6' gap at the Viburnum. Eventually, there is going to be some overlap, but that's how it is as plants grow ... everything always changing. You might want to cover the gap now with a bit shorter plant in front of both (layered.)