You can flick the stem near the flowers or tap on or just shake a larger main stem. The idea is to get the flowers vibrating slightly so they can self pollinate. Usually the wind or a breeze does this naturally when they are outside.
OOOOh....this is to stimulate the flowers..I thought of that botany film which shows the bees legs full of some kind of dust which does the pollination so I’m in visioning qtipping with some kind of dust...thanks.