I've had a Caerulea for about 4 years, and it only bloomed the first year it was in the ground. It dies to the ground in Winter, but always comes back (very) vigorously in Spring and quickly covers an archway - it's already sending up several shoots, but it hasn't bloomed since year 1.

What's wrong? It gets quite a bit of sun (SE exposure) and regular water - very active growth, but no flowers. It's in a fairly dense planting near my front door, so it's competing (successfully) with an over planting of daylillies and irises, and a lilac bush off to the side. I put it there 'cuz I thought it would help it flower to have it's roots in severe competition.