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