Dead space?

Dead space?

I have a dead space behind my shed. By dead space I mean that I was required to sit the shed so that there is so much room (10", I think) to allow for easement between our property and that of our neighbor's line. The beds on either side of this space will be shade loving plants--ferns, hostas, etc. We are doing an entirely white and green garden, BTW. This area is hedged by a cluster of oaks, so it does get morning sun and limited afternoon rays. I have considered putting a big, showy fern back there that would spread, like an Ostritch Fern, since the space will be good for little else. I've also thought about trying to squeeze a small cutting garden in there, although it would be a shame not to see the flowers. So far I've got Purity Zinnias and will soon be buying white foxgloves. Any thoughts? What do ya'll do with unusable space?
Flowers at last!

Flowers at last!

My Bay window succulents.

My Bay window succulents.

More pics!

More pics!

ID help ?

ID help ?

So my mum decided she wanted to redecorate my room while I was at work.. :D

So my mum decided she wanted to redecorate my room while I was at work.. :D

Perenial Blue Flower identification.

Perenial Blue Flower identification.