I intended to catch a shot of our Sweet Potato in a Jar last week which would have been a whole month since we selected it from the grocery store and plunked it in a jar of water. About once a week I changed the water. Eventually, I will have to take it out and pot it. But It can go for months with no problem. I plan on adding very diluted Miracle Grow about one a month. Come back in a few weeks and see how this amazing plant has grown! Great Fun watching it.