I think it lasts longer than 24 hours. I just keep adding fresh pollen to the same container whenever there is a bloom with some and then using when I need it. I just keep it at room temp, and at the end of the bloom season I toss the container (a takeout condiment container). I get close to 100% pollination take rate, and I know that quite often the pollen is several days old. being super precise doesn't seem necessary for me.