I think there actually is science behind it, not just an old wives' tale. Something about the pull of the moon during certain phases making it less than ideal for sprouting, while other times it's opposite. But I don't know a ton about it. I've tried it at times if it was fairly convenient. Sometimes, though, I just ignore it, say if we're supposed to get a lot of rain during the best week to plant. So, who knows? One of those can't hurt, might help situations, right?