We live on Cotswold oolitic limestone which gives alkaline soil, not conducive to growing Heathers. Heathers belong to the Ericaceae family and require an acidic soil to flourish.
The site where we were interested in growing heathers was infertile and at the edge of a stone patio with bits of stone and concrete residue left behind from when it was made. How then to put acid loving plants into alkaline and rubbish soil? Following some investigations, I discovered three happy pieces of information. Heathers can tolerate infertile soil due to a fungi that they have called mycorrhizal which assists them in extracting whatever nutrients they can find from infertile soil. My second discovery was that there are some heathers that do thrive very happily in alkaline soil. As long as the heather has the words Erica carnea or Erica x darleyensis on the label then they will flourish in alkaline soil. I managed to track down over 30 cultivars covering the whole spectrum of heather colours from deepest ruby pink with dark green foliage to white and pink with pale cream and lime green foliage. The third and final discovery was that they like good drainage, which we most definitely have.
We planted small immature Common Box hedging plants (Buxus sempervirens) along the patio edge interspersed with different heathers on either side. As the box matured we began to clip it into the shape of balls. The heather was also clipped so that it snuggled around the bottom of the box balls. Ten years later they are mature - thriving incredibly well - the only maintenance being a quick annual trim.