This was a lovely game. I liked the aesthetic of it a lot and the music was such a banger. It feels SO great to finish a level, to see everything bloom and to hear. Some criticism I have for the game is: if you move diagonally you consume the same amount of water as moving straight. At first it felt a bit like an exploit, but I noticed later on that it was intentional, as some levels couldn't be completed without doing that. The whole diagonal movement is actually a very nice mechanic, making you feel smart for using it.
For example, the execution for the 'vine' elements which appear in later levels (the lines with one pixel to the left or to the right which allow only diagonal movement through them) is wonderful. However, especially for the level that introduces them, I would make the movement area a little smaller. I found myself restarting a few times, trying to uncover some mystical mechanic if I filled the space before the vine, when actually, what I was supposed to do was to simply go through it. If the level had been tighter I would've found that much easier. While trying to wiggle around that level I found that you could go back underground from where you start from. That could also be a cute mechanic, to have a bunch of open soil spots through which you could go.
The last thing I felt like it could be improved was the difficulty. This might be unexpected, but I'd make the game easier. Having just a bit more water so you can go faster through the level without worrying too much about perfect pixel precision would be great and would probably eliminate the need for a slow mode. The game feels great when you can be fast.
Thanks a lot for making this game. That was quite a long review, but despite some criticism I had, I actually enjoyed it quite a lot and I'd love to see it bigger and better!