Some of mine were planted years before they bloomed. As long as conditions (acidic, moist soil; good drainage; full sun) are right (they must beÂyou're in Scotland), they will bloom in time. You didn't ever fertilize them, did you? That would be a no-no and prevent flowering. Other than not blooming, are they growing well? And do you shear them every spring before new growth begins? That is a must, because it makes them fuller with more new (blooming) branches.

This link has a good guide with individual plant info.

Here is a link that might be useful: http://www.users.zetnet.co.uk/heather/handy_guide.html