An enjoyable game with a peaceful ambience - I dig it. At first I thought I was a giant beanstalk growing, then I realised I’m like 3m tall lol. I think a high score game needs a steeper difficulty curve, as especially on normal speed the game’s challenge does not increase quickly enough (it took me a while to figure out I can do growth spurts, which make the game a bit more difficult). More birds maybe? Here’s an idea: add risk-reward for using the growth spurts, for example less water usage or higher point scaling, or add a count-down timer (maybe the sun setting on you, and you have one day to grow as high as you can?). Great work!
PS: I generally like the assets, the music and sound effects, but especially more sound effect variety would go a long way, try to have multiple versions of the same sound for max enjoyment :-)