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