Daaaamn loved this game. Graphics and colour palette were great. Wonderful animations (especially at the end). Music was amazing... great tunes, really made the mood, and changed with the game perfectly. Did you write it for this jam? SFX were good and well done though competed with the music sometimes. Maybe EQ them differently? I dunno.
Gameplay wise it was really fun at the start when it was more challenging, but as other people have said, after a few rounds when you've established a bunch of trees (especially the powerful ones) it's impossible to lose, and nothing to do other than sit there and watch. Which really, at the end, was still fun. But before then, there wasn't much variety. Maybe there could be? Like have another couple of enemy types that get introduced gradually.
Gameplay wise... maybe make the better trees more expensive (like way more, 4 or 5). Have some way that trees die or something. Basically just some reason to stay interactive over the whole time.
Ending was hilarious, kudos.