Really loved the game! Love the premise and really enjoyed the visuals, super well-scoped! I think that a consistent UI for the cost of each upgrade could really help improve the experience. Something like:
Name: X
Effects: +Y (tree icon) -C
Cost: 6 (seed icon)
As you know, gamers notoriously do not like to read 😅
You could also include a +5 food/day right below the food counter to help make things more clear to the player as well.
I also came across this thread for game balancing https://twitter.com/tanyaxshort/status/1301990872645468160 and thought that it might be helpful for approaching balance in your game (not implying that the balance is off, but just want to spread the helpful threads).