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 squash parts.
Grew all possible lilac parts.
Purchased all four plants.
Purchased all plants and all upgrades.
Purchased all garden upgrades.
Grew all possible sunflower parts.
Fruited a flower without growing any extra leaves.
Grew all possible toad lily parts.
Beat the tutorial.