Each individual bloom will last maybe a week - give or take - before looking wilty and the petals start to fall off. It's the bud count and the succession of opening blooms that extend the flowering time of lilies.

"Lilies will bloom for about 2 to 4 weeks, depending on the local climate. The flower time will depend on the number of buds per plant, and the temperature where the lily is planted. More buds on a plant, as well as colder temperatures, will lengthen the bloom time."