Sprout lets you shoot a projectile that opens doors and activate the lilypad the same way you can with fertilize. It also activates dead plants(inactive mushrooms and vine hook points for example). I know we had an issue where getting Sprout without fertilize didn't let it work as it's supposed to or something like that, and I don't think we were able to update it before the 24 hour extension. Regardless, if you have the time to restart and get Fertilize first, it should absolve any issues, but you should be able to fix the issue with whatever save you're at. Let us know if you need any tips/hints!