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 a challenge holding a Critter
Discover the bull and the sheep
Discover letter block P
Take a Critter to the moon
Throw 100 seeds whilst gliding
Collect all crystals
Complete the game 100%
Complete all challenges
Unlock all Telerouters
Unlock all seeds
Ride two Sporchids simultaneously for 400m
Plant 10 Champolines on top of each other
Orbit the entire planet in BALL mode
Rescue MOM
Flower all STARPLANTS
Blast a Critter 100m
Visit all biomes