I'm fairly new to SDBs, my oldest ones are about 3 years old now. Two of my 3 year old ones didn't bloom at all, the other one is getting ready to bloom now, after all my TB iris are winding down. The SDBs don't look crowded really, but should I be dividing them? They looked healthy, & if it helps any, they are Tantara, Bumblebee Delight, & Jazzmatazz. I also have had Boo the same amount of time, but it bloomed early in the season & was full of blooms.