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