As with all cut flowers, cut your flowers before the sun reaches them in the morning or after it has left them in the evening to get the longest vase life.
I am lazy so I have never done the former - but if you do, full kudos to you, you can call yourself a proper flower farmer :)
For the best vase life, you'll want to cut them, just as the buds are starting to crack open. Because these things have so many flowers, I pick some at this stage, and then some that are fully open so my posies have instant wow appeal for the people to whom they are given, but also the buds slowly open over time - for me, I love seeing this happen with my flowers at the kitchen table over the course of a week to ten days.
