I think your best bet would be a low groundcover; whatever would be hardy in your zone. Really too narrow for much else.

looks llike a brand new house ... nothing will ruin a cement wall ... there are problems.. when the walls are already broken ...

that said.. nothing in the shrub category will fit there ...

you could trellis vines.. like clematis.. if for your area ...

or annuals.. what about some sunflowers ...

the tricky part here.. will be watering ... i would recommend a drip irrigation ... some type that self regulating for use and a hillside ... it could easily be done for under 100$ ....

that is one stunning project ... congrats.. keep us posted on its future.. i seem to have some vague recollection of the problem site.. a year back or so??? .. or am i dreaming that????

ken

i use this stuff.. it might be great in those beds also

https://www.youtube.com/watch?v=RCSYeCyuM3c

i did not bury mine ...ken

spirea. barberry. blue star juniper. arbs...many narrow selections. sky pencil holly, if they'll do well for you. dee runk boxwood, couple more similar.

i'll agree the space is narrow, but common varieties of shrubs that will fit the space nicely are everywhere, you just have to do a little digging into what does or does not grow in your area.

but there's another question. what do you want out of landscape? what are you plans? how does this little part fit into the greater scheme, however big or small it may be for you?

There are some spirea for zone 3. Also some small ninebark might fit. Potentilla aren't very tall but small shrubs with flowers. Some small hydrangeas might work or Arctic Fire Dogwood. The dogwood has more winter interest but not very exciting in the summer. Some globe shape evergreens would work but wouldn't add the color you would like.