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.
Vanquish the Grove's Clutch.
Defeat 50 Hayrots.
Complete Goldie's Favor.
Defeat 50 Snowcaps.
Obtain the Silversword
Arrive in Winter Glade.
Roll 100 times.
Upgrade a jar to Grade 4.
Obtain the Flute.
Defeat 50 Glomps.
Defeat the Rotberg once.
Take the Lift to Autumn Town
Upgrade a tool to Grade 4.
Defeat 50 Acorns.
Defeat 50 Shelled Oozes.
Defeat the Octopihi once.
Reduce the Rot Dummy to rubble.
Reach the Summer Bar
Defeat the Bookworm once.
Defeat 150 Enemies.
Wake up in Spring Hamlet.