Here is the full list of all 21 Plantera trophies - there are 21 bronze.
Scare away 500 birds
Scare away 100 foxes
Scare away 100 wolves
Scare away 100 bunnies
Buy 3 garden expansions
Buy 6 garden expansions
Buy 12 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 10.000 Coins
Gather 100.000 Coins
Gather 1.000.000 Coins
Reach level 10
Reach level 50
Reach level 100
Collect 500 butterflies
Bash 50 moles
Collect 10 ladybugs