Most bulbs need to be dug up and parted out because they will stop blooming after a few years.Once parted out and replanted you should be good for a few more years.
Here are some reasons why bulbs do not flower (It's OVER, Baby...):
- OVER-watering: Most bulbs come from a hot climate and have dry summers.
- OVER-done: Bulbs that have dried out or gone soft or moldy.
- OVER-time: Bulbs that are planted at the wrong time, without enough cold time to develop
- OVER-shade: Not enough sunshine
- OVER-crowded: Too many bulbs grow together and the blooms get smaller and smaller and eventually stop blooming
- OVER-eaten: Munched on or dug up by animals, like moles or deer
- UNDER-planted: Too close to the surface exposes the bulbs to frost and wind drying.