Far, far too narrow for any tree.

You might be able to get away with yews for a bit. You'll have to prune them and look for the right cultivar for your situation. It's possible. They would fill in better than sky pencil so you wouldn't need as many. Not really going to provide shade.

As said previously, far to narrow for any tree or large bush. The only thing suitable for that area are perennial flowers and such. Even they may fail as there will be an occasional person who walks in that area or rides a bike.

If you are in the north and there is a street opposite the fence, you may also have salt problems use on the street in the winter.

tree needs to be 10ft tall at mature

==>>>

no tree stops growing at some magical height ... which then means signing up for a lifetime of pruning.. and who wants to do that at 10 feet tall ... as you age.. you will find it can become a problem ... and it sure doesnt sound like hiring it out is in the budget ....

the stones and fence are its own architectural statement .... i dont understand why you want to cover it ...

you might add some trellises to grow clematis or other minor vines up to it .. to accent it.. but not cover it ..... but.. imo.. not monster vines that cover it ...

ken

for future reference.. include your big city location... when asking about what plants might grow in your area ... it helps in nearly every post ...

ken

The only trees which would fit there would be espaliers and even they would need constant and extra vigilant maintenance to keep the path clear.

this is in Seattle, zone 8, facing west. I've seen someone 3 blocks away grew a huge tree in that space though idk what kind of tree or how that's possible. unless the tree has deep deep roots and just reach far down the surface where there's large space ?

will post a pic later

Yews are great advices thanks

when I say 10ft tall at mature, I thought every nursery that sells trees would tell u the mature height width? that's all I meant. a small tree at 10ft mature height

A two foot wide space, with a retaining wall and fence on one side and a sidewalk on the other, is not enough room to accommodate any size tree. You are looking at some sort of hedging shrub and also frequent pruning to keep width in check.

I would also question the need to cover or disguise what is a perfectly attractive wall and fence. What is wrong with the low growing plants already in place? As small as they are (in comparison to any tree or hedging shrub), they are already filling the area.

btw, the "mature" size of any tree or shrub is only a ballpark figure. As noted, they will continue to grow indefinitely. A 10' tall tree - and there are very, very few that would qualify - will not stay at 10' forever. The longer it lives, the taller it will get. And it is really the width of any plant used here that would be of greatest concern.....almost anything with any height will exceed that width.

the reason is the fence on top of the stones have large gap in between so people walking by can see through. I guess I could always fill in those gaps with boards though I like trees and plants....

this is the tree that my neighbor has, growing in small space next to the stones

Can anything be planted on the other side of the fence?

It will be ineresting to see that other tree.

tj

so is this one. I wonder if they just have deep root allowing them to reach more space

yes I've already planted on the other side of the fence.

these crape myrtles too but they are smaller

these crape myrtles too but they are smaller

though I will admit all of them have slightly bigger space then mine and they don't have the vertical stone right up against the strip

Pretty sure those are not crape myrtles :-)

are these yews?

well anyway, thanks everyone for your advice. I might try a skypencil or yew, but it seems unlikely to plant a big tree.

Unless someone is doing nude sunbathing in the front yard, those gaps are not significant enough to bother covering. Folks walking along the sidewalk are not going to bother with stopping to peer in between the gaps to see what's happening on the other side :-)

I think you are worrying unnecessarily.

haha no nudity

Yes you could grow a few trees in that space. No they cannot be 10' tall max. The lowest branches need to be at 7'. It is possible and it would look better than a high maintenance row of bushes ruining the nice look of the block wall and fence because you are afraid people can see through the fence slats. Nobody is thinking about you when they are out for a walk.

A number of plants could be possible for small trees in that space. Except. I see a utility pole in the distance. Are there wires overhead?

That first tree you showed had great bark. It looked like a Eucalyptus or an Acacia. Wrong tree for the sidewalk though. I bet it annoys a lot of people out walking. A lot of the other shrubbery you showed said routine sidewalk trimming. You up for that?

If the entire goal is to make the fence denser just plant some climbing plants and train those to spread out on the fence.

The ”crape myrtles” are rose bushes.

Rose bushes on the sidewalk. I would hate those people.

No to a tree. As previously suggested, at most a trellis arrangement, but those little shrubs will look fine depending on climate/growth factor.

Maybe try espalier pruning...

https://www.thisoldhouse.com/landscaping/21017607/grow-espaliered-trees-for-a-slim-fit