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