Posted: 06/01/2013 at 21:40
Same sorry story for me too when we moved into our renovated house six yrs ago - builders rubble buried all over the garden.
What to do? - well I did do the hard work in clearing it and improving my soil and now we get Silver in our local 'in Bloom' comps.
Alternatively you could make use of the poor soil and utilise it for plants that like those conditions - quite an opportunity really - rather like the earlier suggestion of Buddleia and other wildflowers.