This is an unpruned gallon of Calluna vulgaris. The old flowers will fall off leaving long lengths of bare, unsightly stems. Prune these off at the base of the old flowers, or you will have an ugly plant in a few short years.  They will grow out quickly again, don't worry!

 

This is what it should look like pruned. This will keep it bushy and prevent it from forming a bare, woody center.

                

In the colder zones, prune in spring. Warmer climates can prune when finished blooming or in the spring.

Pruning