Some of them bloom and the flowers last quite a while (say 2 months or more) while others last only 20-30 days. They begin to wilt one at a time then fall off of the stem. Some of the stems will start to shoot out new buds just before the old flowers fall off, but if not, I just cut the old flower stem off about 1" or 3-4cm from where it pokes through the leaves.

This post may help .. @bdmillergallery/time-for-another-orchid-update