Here is the full list of all 29 Plantera achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Have planted a total of 100 trees
Reach level 100
The Loot Hero have appeared 50 times
Collect 500 butterflies
Grab gold 1000 times from the Loot Hero
Have planted a total of 100 plants
Bash 50 moles
Have planted a total of 100 bushes
The Loot Hero have appeared 25 times
Scare away 500 birds
Scare away 100 wolves
Reach level 50
Scare away 100 foxes
Buy 25 garden expansions
Grab gold 500 times from the Loot Hero
Have bought a total of 100 animals
Scare away 100 bunnies
Trash 10 items
Buy 15 garden expansions
The Loot Hero have appeared 5 times
Gather 1M Gold
Collect 10 ladybugs
Gather 100k Gold
Buy 5 garden expansions
Gather 10k Gold
Grab gold 100 times from the Loot Hero
The Loot Hero bashed a mean critter!
The Loot Hero has appeared!
Reach level 10