Garden Wall..

Anella Bennett

I'm looking for advice on what to plant down by the main gate.. I have one photo I took when I was clearing the area. I am aware that the wall needs re-cementing! What are the best plants to grow on top of that wall that do NOT require any (or as little) attention as possible? Heather? Would that be any good? Before I cleared this area, there was nothing but weeds.
Since this photo was taken (this was the day I cleared it), I have scattered some Miracle Gro mixed flower seed, simple blue and red flowers just so that it doesn't look bare! Unfortunately the weeds are growing in-between these and I am looking for something I can just leave well alone and it can fill the gaps. Also, any tips for the bottom of the wall. The small rocks have been replaced with larger ones since this photo was taken!