Arborvitae, but not if they have lots of deer in the area!

Western arborvitae like 'Northern Spire' are deer resistant.

It looks like a fire pit area next to pool patio, so beyond that instead of right against pool patio? Like following fence line? If that is 6' high, then doubling that to 12' for a fence line planting would block the neighbors where the 4' grade drop doesn't matter at the higher pool. And the distance clear should be based on the plant selection, 5' is probably not enough for the type of plants needed for screening.

Is the dark fence on the property line? Is it part of the pool fencing so that the new trees/shrubs/plants will be inside the fenced area and deer are not an issue?

What is the measurement from the dark fence to the edge of the pool pavers?

The farther away from the pavers that the conifers are planted the better imo. It leaves more room in front for shrubs and plants and a grass strip between the pool pavers and planting bed. The landcapers can create a low berm to plant the conifers in to raise them up from the 4’ dip.

Depending on whether deer can get at the conifers and the measurement from fence to pavers, spruces or thuja ’green giant‘ may work. They get large and deer will browse them in my area.

‘green giant’ would get WAYYYY too large- this needs to be something that doesn’t get wider than 3-4’ wide. Even ‘emerald green’ will be too big… but no, deer are not a concern, as the yard is fenced in. And you are correct 3onthetree, the “screen” will actually be bordering the fire pit rather than directly next to the pool. My bad :-)

And yea 3ontgetreeqy

I am surprised that you say ’emerald green’ arborvitae is too large. It gets 3-4’ wide x 10-15’ tall at maturity which seems to fit your requirements for width. They can be lightly pruned to control size.

Perhaps a narrow Japanese holly variety such as ’sky pencil‘ which matures to 2-3’ wide x 10’ tall.

To fully screen the neighbor’s house may require something 15-20’ tall at the fence but it’s hard to say for sure from your photos. Have someone stand with a long pole held straight up in the planting area to get an estimate of how tall the plantings need to be to screen the neighbor’s house.

I didn’t receive any notifications about these comments and I’m just now seeing them, I forgot to check lol. And thank you for the suggestion of standing with the pole in the area, that’s great advice and I will pass it along.

Also I know that’s what garden shop tags say about the mature growth size of ‘emerald green’ but I’ve seen plenty around bigger than 3-4’ wide, it’s important to keep in mind that the tags tell you what to expect at around 10 years and trees being trees, they will continue to grow after that. I know she was hoping for something that she doesn’t have to prune at all… she may have to give up on that hope though!