This is a test of commonsense. Complete the next sentence:

How to get irises to bloom
Be aware that irises need to be divided.
The first and most likely cause for irises failing to bloom is overcrowding. Irises must be dug up, divided and replanted every three to four years.
If this does not happen, it becomes less likely that your irises will bloom. Cut the leaves down to a height of six inches.