I think there's a good core gameplay loop and I'm excited by the potential for complexity that it offers. And the game itself it just nice to look at! The details around the play area like the path and flowers and rocks are really cute, and I like how you used a little forest area in the lower right of the screen to reduce the amount of negative space there. Also, the way the cards wiggle and bounce are fun without being too visually noisy, and that the cursor changes from the arrow to hand to closed hand is a cute and thoughtful detail. :3
The "tool" cards as we called them were supposed to do similar things to what you mentioned. we cut them out for time purposes, though I'll admit they weren't as interesting as they sound.
I agree usually you feel like you'd like water to be optional instead of mandatory, though I think thats more the result of simplifying the water layout and raising the card value maximum, both of which butchered the original water mechanism lol. I like the sound of the compost bin! If we work on this further I'll give a try and see if discarding the highest cards isn't always obvious.
Thanks a lot for the suggestions!