Here is the full list of all 9 Reach for the Sun achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Grew all possible toad lily parts.
Beat the tutorial.
Purchased all four plants.
Purchased all plants and all upgrades.
Purchased all garden upgrades.
Fruited a flower without growing any extra leaves.
Grew all possible lilac parts.
Grew all possible squash parts.
Grew all possible sunflower parts.