Hey! Thanks for playing. The feedback is more than fair haha.
I've since the jam release been working on an update to make things clearer. There will be a description for each item/upgrade, explaining what they do. Sprinklers and sheep will show the area in which they work.
I want to make water tiles more useful by having them contain fish, which will also be a way to get points.
I suppose the "tutorial" text could be easily missed if you only see the grass tile, so some kind of visualization of the growth of a tile could help. It could show that you're about to be game over (which happens when a sunflower is dead for too long)
Thanks again for playing, and giving valuable feedback!