The first potential problem is hot weather or over-watering. Too much heat can be damaging to calla lilies, and if they have been overwatered, they can develop root rot or die back and become stunted in growth or bloom prematurely. Additionally, if these plants are planted in too shady of an area, they may not bloom very well at all - so it's important to find the right spot for them that gets just enough light throughout the day.