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