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