I really enjoyed this, however I think the scaling needs a lot of work. It feels like it takes forever to be able to upgrade the actual mower for the first time, and once you do you can max level it in the time it took to to unlock the first level up.
The grass growth and auto mower didn't really feel needed at all, and after maxing the mower I maxed the grass growth, which started to make the game lag.
I think one of the main balancing things would be to lower the original price of the first level up, and to make that price increase each time you do.
You could even make the level up changes a little more gradual so that there could be more total levels.
I also wish there was some music or mowing sounds.
Overall great game!