Tool to neatly trim grass atlow wall edge and between flowers

I usually cut my grass with ride-on lawnmower and can cut areas near ditch with strimmers.

However I have flowers sowed a certain distance apart near a lovely stone wall and it is between the groups of flowers and also close to the edge of the wall I want to tidy up. It looks a bit sloppy with grass slightly hanging over wall or just too much of it between the flowers. I don't mind spending a bit of time at it but something good that would work

Is there any smaller tool I could buy that would do a neat job as strimmers is just a bit too big. Any smaller versions of them or something similar?