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