Thanks for playing our game.
We worked really hard to get planting and some other things done - but time was just too short. So the "Plant" button doesn't have any implemented action. The goal you can go for: Wait until new (and later rare plants) grow by themselfs under their needed conditions. When you click on them, you harvest them for points, and unlock the respective Almanach entry. Once all Almanach entries get unlocked, you can consider winning the game.
I just finished the Lore for our game - in section "Lore" you can read how the game was supposed to be played: https://sealnf.itch.io/natura