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