By Wishbone
United Kingdom 
Why do some of my perennials fail to flower
29 Aug, 2011
Answers
generally the reasons are:
too young, sulking due to being moved/planted,
incorrect light levels [too sunny for shade lovers and too shady for sun lovers]
But as MG says which plants in particular?
29 Aug, 2011
Previous question
There are lots of different reasons which perennials are you referring to specifically?
29 Aug, 2011