Here is the full list of all 21 Garden Story achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Defeat 50 Snowcaps.
Complete Goldie's Favor.
Vanquish the Grove's Clutch.
Upgrade a jar to Grade 4.
Upgrade a tool to Grade 4.
Obtain the Silversword
Arrive in Winter Glade.
Defeat 50 Hayrots.
Defeat the Rotberg once.
Take the Lift to Autumn Town
Defeat 50 Acorns.
Defeat 50 Glomps.
Reduce the Rot Dummy to rubble.
Defeat the Octopihi once.
Defeat 50 Shelled Oozes.
Obtain the Flute.
Reach the Summer Bar
Defeat the Bookworm once.
Defeat 150 Enemies.
Roll 100 times.
Wake up in Spring Hamlet.