What to plant?

East facing front garden with 6 foot high hedge- with established roots but also very tangly shallow ones. The soil is quite heavy . There is a border of sorts in front of the hedge. I have tried a few shrubs but though they have clung to life, they haven't really flourished. Any ideas what might grow there? I'd like to get a tiered effect if possible.

 

Finally found out what they were!
Forsythia, flowering current, weigela and not sure what else. None had died, but they hadn't grown either and one was losing it foliage from the top down.
I don't want to put anything that will grow more than 1.5 - 2 m high, and would be happy with herbaceous perennials but not just hostas.

 

Forsythia have very fibrous roots. Not much depth but draws a lot of moisture away.
I could get very little to grow near it, so dug it out.
I needed to put plenty of compost in to enliven the soil. Other things are now growing fine.