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