It is only normal if the flowers have been open for at least two weeks. Anything less then that is not normal.
Under proper watering and temperatures they should last between three and four weeks.
But good culture and good growers know it is about light, temperature, air movement, humidity, watering and pots/media. If one component changes more then a little bit, it has a profound effect on all the others. The good growers know how to keep everything in balance.
