I watched a number of videos on how to grow sweet potatoes (Click this , for instance) and heard that you had to put the sweet potato fat end down in the water, so I decided to test this suggestion, and it looks like it might not be true. I selected two seemingly-similar sweet potatoes and put them both in jars with water covering the bottom 2 inches or so (fat end down) of the sweet potatoes, then set them on a sunny windowsill in late January of 2021. One sweet potato failed to grow any ‘slips’ (new vines) so I thought maybe it was a dud and almost composted it. Instead, I cut the dud spud in half and put both the fat end and the narrow end in their own jars, cut side down. It took weeks longer, but the cut potato parts ended up sprouting vigorously also, just like the whole potato with the fat end down. Being in zone 6B, I had plenty of time to wait (since I started this in January), so the fact that the cut potatoes took longer to create slips wasn’t a problem. It’s April 22 now and I have lots of slips, which will probably be getting planted in a couple weeks. It’s really hard to wait until Mother’s day to plant these summer crops! Some of my leftover winter crops, like kale and swiss chard, are still doing well.
I can’t conclude too much from this experiment, but it looks like a few more slips were generated from cutting the sweet potato in half and putting the halves into water than just setting the whole sweet potato in a jar of water. Both ways seem to have worked, in that slips were produced via both methods. You Choose!