I must say, the character animations here are impressive and expressive. The other art on display is also very good, even if the colors could clash less.
However, the puzzles, which seem to be the key part of the game, are kind of boring.
Perhaps for each plant, a different type of puzzle? And for every plant already made, the puzzles could get more complicated. For example, on stage 1, the bubble puzzle would require a combination of 3 key presses, and 4 on the next stage, and 5 on the stage after that, and so on.
The bubble puzzle could use a timer. Even if it was a more forgiving one, that could make the puzzle more engaging.
The jigsaw puzzle could also use a timer. Otherwise, it's fine as is.
Continuing on the bubble motif, maybe there could be a Simon Says type of ordeal?
Outside of the puzzles, it's crazy how Marina simply doesn't run out of sand or seashells.
Maybe if you made too many plants to hold, you could place them in your room for later?
I might write more if I think of something.