Here is the full list of all 18 Grow Up achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Complete all challenges
Complete the game 100%
Discover the bull and the sheep
Bounce on a Youch 7 times without touching the ground
Discover letter block P
Throw 100 seeds whilst gliding
Complete a challenge holding a Critter
Unlock all seeds
Ride two Sporchids simultaneously for 400m
Blast a Critter 100m
Take a Critter to the moon
Plant 10 Champolines on top of each other
Orbit the entire planet in BALL mode
Collect all crystals
Unlock all Telerouters
Rescue MOM
Flower all STARPLANTS
Visit all biomes