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%
Throw 100 seeds whilst gliding
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
Rescue MOM
Unlock all seeds
Take a Critter to the moon
Discover letter block P
Flower all STARPLANTS
Bounce on a Youch 7 times without touching the ground
Visit all biomes
Blast a Critter 100m
Plant 10 Champolines on top of each other
Complete a challenge holding a Critter