Suggestions for thin shallow border

WildFlower_UK

We've just recently had a new patio laid in our garden's sunniest spot (South Facing). We asked the patio people to only pave up to the fence posts to allow us easier access to the fence should anything need replacing in the future.

Our initial idea was to fill in this gap with decorative stone. However I am wondering whether anything could be planted here? Our soil is clay, and the space is about 20cm wide. Concrete was used to fit the slabs so there's no soil to the patio side (except underneath the patio foundations at about 25cm below top level), and soil fence side.

Do you think anything would thrive here? Open to all ideas; climbers, grasses, flowers (although I don't really like bedding plants personally).

  

Greenbird

Too narrow and dry. 

Some small outdoor succulents perhaps, but they'd have to be brought back in for winter.

Hostafan1

I'd remove the 3rd slab from the front , just beyond the post and improve soil and plant a climber in there to spread across the fence.

Loxley

Erigeron karvinskianus would probably be at home there, and the usual things people plant in wall crevices (aubretia, sedums etc). Erigeron would have more impact though. If you plant these things in Autumn they're more likely to develop the root systems they need to see them through a dry summer. You could plant a climber to the left (in open ground) and train it across.

lilysilly

I would go for Mexican fleabane, erigeron karvinskianus too. It flowers virtually all year around these parts, Devon, in the smallest bit of soil along the base of walls and in any pavement crack. 
I would buy a packet of seed and scatter it all along that little strip. Rake the soil first and break up any big lumps, then water, then sow. I found that the easiest way to introduce it .

JennyJ

The erigeron doesn't flower all year here, although it does start early (already in full flow) and continues late, and it is reliably evergreen.

WildFlower_UK

Thanks all! Erigeron sounds like a lovely idea, so will give it a go. Worse case scenario, it doesn't work and I have to just go with Plan A.